A hundred years before the emergence of Swift and blockchain, the Chinese had already built their own cross-border financial network.

Writing: Little Biscuit, Deep Tide TechFlow

Recently, “Love Letter to Grandma” has been flooding social media. Douban score 9.1, the highest domestic film rating since the 21st century, a dark horse at the May Day box office, surpassing 200 million yuan and still gaining momentum.

The film tells the story of a letter that arrived half a century late. In the 1940s Chaoshan, a man went south to Southeast Asia to make a living, leaving behind a young wife and three children. He died abroad, and out of gratitude, the daughter of the innkeeper impersonated him and wrote 18 years of letters to his wife, sending money all along.

In the movie, those crumpled pieces of paper, called “pi” in Chaoshan dialect. Letters and money sent back from overseas Chinese are collectively called “Qiaopi.” It sounds rustic, but if you understand a bit of financial history, you’ll realize:

This thing is one of the most incredible cross-border financial networks in human history. It predates Swift by a hundred years, and blockchain by a hundred and fifty. Entirely private, peer-to-peer, no central clearing, operating across sovereignties, supporting nearly half of modern China’s international balance of payments.

Its entire credit foundation is a phrase in Chaoshan dialect: “Trust is greater than life.”

A forgotten financial infrastructure

First, look at some numbers to understand how impressive this was.

Qiaopi originated in the mid-19th century. The earliest physical Qiaopi found dates to 1881, but it may have operated even earlier. It continued until 1979, when the business was integrated into the Bank of China system, lasting over a hundred years.

There are about 170k existing archives, with 160k from Guangdong (over 100k from Chaoshan), and about 10k from Fujian. These are survivors of the wreckage. At its peak, the annual inflow of funds into China via Qiaopi reached billions of dollars. During the Anti-Japanese War (1937–1945), Qiaopi remittances accounted for over 50% of China’s foreign exchange income, holding half the country’s foreign reserves.

Chen Jiageng alone used Qiaopi to send money home, founding Jimei School in 1913 and Xiamen University in 1921. A complete modern university was built with these crumpled letters.

Even more astonishing is its operational mechanism.

For most of the period before 1979, this network operated almost without any government endorsement, central bank backing, or official clearing systems. No Swift, no foreign exchange controls by the central bank, no cross-border correspondent banking accounts—nothing.

What did it rely on? Three things: water carriers, pi offices, and a concept called credit—today’s financial industry’s most scarce and precious resource.

Water carriers: the human version of on-chain nodes

The earliest Qiaopi had no formal offices, relying entirely on “water carriers.”

Water carriers were professionals who traveled on red-headed boats between Southeast Asia (Nanyang) and Chaoshan, Minnan. They sought compatriots at mines, rubber plantations, docks, collecting letters and money from households, then tying the money to their belts. The money was literally strapped to their bodies, and upon returning to China, they delivered it door-to-door to the recipients.

Sounds primitive? But this mechanism has several features that would make modern financial experts exclaim “Wow”:

First, it’s peer-to-peer. No intermediary clearinghouse. From the moment the remitter hands over the money to the water carrier, until the recipient receives it, the money never passes through any bank account or sovereign currency system.

Second, it’s identity-verified. Water carriers are usually fellow townspeople who know both parties. This is a form of authentication more reliable than SSL certificates—you can’t run from your hometown. In a Chaoshan village, the water carrier knows who lives where, how many family members, and the kinship network.

Third, its default rate is nearly zero.

This point deserves special mention. In the 19th and early 20th centuries, water carriers had no collateral, no insurance, and no legal recourse. They often carried the entire savings of dozens of households—equivalent to millions of RMB today. If a water carrier ran away, no one could catch him, and no one could make him pay.

But they never ran.

Why? Because the essence of this business is trust as the only collateral. If a water carrier runs once, his entire reputation among the Chinese communities in Chaoshan and Southeast Asia is instantly destroyed. His entire life in the Chinese diaspora would be over. The cost of being permanently ostracized by the community is far greater than any legal punishment.

Pi offices: from P2P to a network of financial institutions

Over time, water carriers became more professional, leading to the emergence of pi offices—specialized Qiaopi businesses.

The appearance of pi offices upgraded Qiaopi from “personal peer-to-peer” to “institutional network.” But unlike modern banks, pi offices remained private, family-run, and networked—one in Southeast Asia, one in the hometown—woven together by kinship and community trust.

How sophisticated was their capital flow? Let’s break it down:

Step one: A Chinese in Southeast Asia, A, walks into a pi office, hands over 100 Thai Baht, and instructs the office to send it to family B in Chaoshan.

Step two: The pi office immediately issues a “pi” (letter + remittance slip), which might be denominated in Hong Kong dollars or foreign currencies, but rarely in Thai Baht.

Why not Baht? This is one of the cleverest aspects of Qiaopi. Early cross-border pi offices used Hong Kong dollars as the settlement currency because it was pegged to the British pound, highly liquid, and recognized throughout Southeast Asia. It became a de facto supra-sovereign currency for the Chinese diaspora in East Asia.

It’s somewhat similar to today’s crypto demand for USDT/USDC—cross-border, avoiding exchange controls, highly liquid, accepted by all parties.

Step three: The Southeast Asian branch of the pi office transports the letter and remittance instructions by ship back to the corresponding pi office in Chaoshan, but the money may not actually be physically shipped.

This is the key. A mature pi office establishes long-term relationships with import-export merchants in Southeast Asia. Money sent from Southeast Asia to China (Southeast Asia → Chaoshan) can be directly used to pay for imported goods. Conversely, funds from China to Southeast Asia can offset each other. The actual cash that needs to cross borders is only the net difference.

This mechanism is today called “netting.” The Swift system processes hundreds of trillions of dollars daily, essentially doing the same—pi offices have been doing this for over a century.

Step four: Upon receiving instructions, the Chaoshan pi office dispatches “pi runners” to deliver. These runners often walk dozens of kilometers, going door-to-door, reading and writing letters for illiterate women and elders, confirming receipt. The “return pi” then travels back to Southeast Asia, completing the transaction loop.

No bank accounts, no government oversight, no central clearing—yet it ran steadily for a century.

Dark pi and Dongxing Exchange Road

The most legendary stories of Qiaopi occurred during wartime.

In 1939, Japanese troops occupied Shantou, cutting off the normal pi remittance routes. Half a million overseas Chinese families faced economic collapse.

At this moment, overseas Chinese created a legendary underground remittance route.

Goods traveled by ship from Southeast Asia to Haiphong, Vietnam, then crossed the border at Dongxing, China-Vietnam border, carried by porters into Guangxi, and then back to Guangdong. This route was called the “Dongxing Exchange Road,” and at its peak, annual remittances still reached hundreds of millions of yuan.

When the sovereign financial system collapsed amid war, the civilian financial network temporarily built a new channel.

Even more astonishing was the “dark pi” system. To evade Japanese and later Kuomintang inspections, overseas Chinese used coded language in their letters. “A bag of rice” represented a certain amount of silver dollars, “five salted fish” represented a certain amount of Hong Kong dollars. This secret code system operated in the minds of water carriers and pi runners, so even if the enemy intercepted the letter, they couldn’t understand it.

During the Anti-Japanese War, Zhou Enlai personally wrote a thank-you letter in Wuhan to Cuban Chinese Tan Yixi, because this overseas Chinese hid anti-Japanese donations inside Qiaopi and delivered them directly to the Eighth Route Army’s Wuhan office.

What does this mean today? It’s akin to a scenario where, under sanctions on the US dollar, disconnection from Swift, and frozen bank accounts, overseas Chinese rely on a grassroots consensus network to send hundreds of millions of dollars annually to designated recipients.

Is this “censorship-resistant transactions,” “off-chain ledger systems,” or “civilian stablecoin clearing networks”? The inventors of these concepts don’t know—they only knew: grandma at home was waiting for money, children needed to eat, and the country was at war.

An unrepeatable financial miracle

Qiaopi and blockchain, Swift are different interpretations of trust.

Swift is state-backed trust, built on sovereign currencies, central banks, commercial banks, and regulatory coordination. Its strength depends on the stability of the entire international order. Crypto relies on cryptography and code-based trust, attempting to replace human and institutional trust with mathematics and consensus algorithms.

And Qiaopi?

Qiaopi is rooted in clan, kinship, local customs, and social trust. It has no mathematics, but it has genealogies, accents, and hometown dialects. Its core operation is based on a cultural consensus that defaulting is “social death.”

This is what modern finance most desperately needs—trust itself is collateral.

Today’s so-called “innovations” in finance—collateral, guarantees, regulation, insurance, legal recourse, credit scoring, KYC, AML—are all attempts to compensate for the disappearance of this trust. We use increasingly complex systems to try to restore that simple state: “A water carrier carrying a village’s money and not running.”

The difficulty of this lies in the human element.

During the Guangxu era, overseas Chinese in Thailand, Yang Jie, sent a Qiaopi home with only ten words: “See the letter, urgently redeem my daughter and bring her home.” When the remittance was cut off, his wife was forced to sell their daughter. Upon learning this, he was heartbroken and hurriedly sent 50k yuan home, only able to write “urgently” and no more.

In Singapore, a female overseas Chinese street vendor, Chen Lianyin, couldn’t bear her life, and upon hearing her mother had injured her foot, she saved every penny to send money home: “The elder has frequent meals shortages, leading to foot injury, unable to leave the crutch; the daughter cannot help but cry.” She called this “family sin.”

In the film, the last letter Grandma received read: “Though Siam is far, my heart is with you; as if near, stay safe, and we will reunite.”

Most Qiaopi amounts were 5 HKD, 10 HKD, or 50 HKD, sent in small parcels, year after year. Over a century, generations of Chinese, thousands of pi offices, tens of thousands of water carriers and pi runners, delivered small sums, words of peace, across war, revolution, upheaval, famine—faithfully reaching homes in Chaoshan, Minnan, Wuyi, places they might never return to in their lifetime.

The financial engineering behind this has no modern payment system can replicate under similar conditions.

And all its technology stack? A red-headed boat, a familiar accent, a faded belt, and the four words: “Trust is greater than life.”

In the past decade, the grand narratives of crypto—decentralized cross-border payments, permissionless financial networks, bypassing Swift, civilian stablecoins, trust as collateral—have already played out in those forgotten villages along China’s South Coast, in the hands of illiterate grandmothers and grandfathers, uneducated water carriers, and faded belts. For a hundred years.

This is a story about trust—most humble, yet most magnificent—that we may never fully return to.

Dedicated to all who have written, signed, entrusted, and received on that yellowed paper.

And to all who are still trying to rebuild this trust network today.