SWORD GATE PASS, SICHUAN PROVINCE, CHINA“Over there!”

It is my walking partner Li Huipu. Li points to a line of cypresses near a highway that booms with the inescapable red cargo trucks of China. (All of modern China is a construction site.) A few miles farther on, she peers down from a concrete bridge into a steep, rainy mountain gorge. “It’s down there!” she calls out again. “See it?” She is a resourceful hunter. She a woman of Shu.

We are stalking the old Shu Roads.

What are Shu Roads—the Shǔdào? 

They are squared slabs of stone—of slate? of granite?—about the size of small tabletops. Placed by hand in times long past, and numbering perhaps in the millions, they pave forgotten byways that cross the mountains dividing northern from southern China. Antique but sturdy paths. They unspool like gigantic question marks over miles of jagged landscape. They start and stop and fade into shadowed forests. Time machines. Broken mazes plied by phantoms. Sparse and solitary and moving. We try to walk them, Li and I, through the uplands of Sichuan Province.

In this way, we hopscotch through centuries. We skip between the chaos of the Warring States Period in Chinese history, circa the fourth-century B.C., and the distractions of the dynasty of TikTok.

The laying of the Shu Roads began when the Romans built the Appian Way—some 2,300 years ago—and for the same purposes: military control and trade. The vast Eastern Zhou empire was cracking apart. A subject kingdom called Qin, occupying much of modern-day Shaanxi Province, rose to power. It pushed new roads across the 12,000-foot Qin Mountains to attack a wealthy southern rival—the kingdom of Shu—centered in today’s Sichuan. Rich in salt, silk and iron, Shu expanded its own roads to better defend its mountain frontiers. But Shu lost in 316 B.C. And all these stone-paved roads, improved with post offices and caravan stops, became arteries of imperial integration. This was when China’s center of gravity lay in the highlands of the west, and not (as today) in the hot, low plains and cities of the east.

A hundred generations of traders commuted along the Shu Roads. They pushed “wooden oxen”—wheelbarrows. Armies fitted in leather armor marched atop the branching network of flagstones. Sometimes, they torched wooden sections of the road—miles of extraordinary plank walkways suspended from canyon walls—as they retreated. Farmers hustled their goods along the roads. (One segment was called the Lychee Road, dedicated to a royal concubine’s fondness of the fruit.) Poets and sages walked the roads. So did deposed kings, refugees, addled foreigners, and elderly farm women tacking against gravity under bundles of firewood. (A few last of these still walk the trails today.) In China’s relict wild mountains, giant pandas, red pandas, gnu-like takin, and six-foot salamanders also prowl the Shu Roads. Today these weedy paths go mostly nowhere.

The Shu Roads welded north to south China. They also became tangents of longing. They delivered art.

In the eighth century, Du Fu, a titan of the gilded age of Chinese classical poetry, survived on boiled tree leaves in a hut in Chengdu. Exhausted from escaping rebellions, constant joblessness, and years of itinerant wanderings along pitiless Shu Roads, Du Fu mocked his so-called-poet’s life:

Far from the market, my food has little taste,
My poor home can offer only stale and cloudy wine.
Consent to have a drink with my elderly neighbour,
At the fence I’ll call him, then we’ll finish it off.

His contemporary, the traveling bard Li Bai, lamented his journey into exile along the slippery roads up the Qinglin Mountains:

The Shu Road is as perilous and difficult as the way to the Green Heavens.
The ruddy faces of those who hear the story of it turn pale.
There is not a cubit’s space between the mountain tops and the sky. 

In Chengdu, the Shu Roads dream mutely under asphalt. Li and I hike toward their northern terminus some 400 miles away, to Xi’an, the capital of Shaanxi Province.

Near Minyang we cross the ghostly path of a British traveler in a long Manchurian dress.

Sometimes Isabella Bird walked. Sometimes Bird rode a chair hauled by laborers who cushioned their aches with opium.

“A thousand years ago it must have been a noble work,” the British traveler wrote of a still-bustling Shu Road in The Yangtze Valley and Beyond, a record of her travels in western China in 1897. “It is nominally sixteen feet wide, the actual flagged roadway measuring eight feet. The bridges are built solidly of stone. The ascents and descents are made by stone stairs. More than a millennium ago an emperor planted cedars at measured distances on both sides, the beautiful red-stemmed, weeping cedar of the province . . . Each tree bears the imperial seal and the district magistrates count them annually.”

They still do.

To locate old Shu Roads, Li and I seek out colonnades of big trees linking village guesthouses and gritty truck stops. They aren’t cedars. They are cypresses (Cupressus). A few are 800 or more years old, and each one is tagged by the Sichuan reforestation bureau. In the wet mists of Sichuan their massive black boughs drip their own rain.

Isabella Bird wrote sympathetically of rural Chinese. She did complain about the 19^th-century bureaucracy. Qing Dynasty officials demanded her passport every few miles, she grumbled, copying her particulars on clipboards of slate. This also still happens. At Wulian, an empty inn cannot host us. They aren’t registered to receive foreigners. Two police drive us to their station. They help us fill out the necessary paperwork.

“Why are you walking?” the older cop asks, skeptically.

“It’s a walking project,” the younger cop reminds him. He rolls his eyes at his square partner. “It’s about walking.”

Marco Polo may have paced off Shu Roads in the 13^th century. He supposedly journeyed from Beijing to Chengdu: “Having traveled those twenty stages through a mountainous country, you reach a plain on the borders of Manzi . . . where you see many fine mansions, castles, and small towns. The inhabitants live by agriculture. In the city there are factories, particularly of very fine cloths and crapes or gauzes.”

The first and only empress of China, the supremely brilliant and capably ruthless Wu Zetian, may or may not have been born on a Shu Road five centuries earlier. The northern Sichuanese city of Guangyuan claims her in any case. Its museum of mannequins celebrates the world’s “top 10 queens.”

We trudge on, Li Huipu and I. Stone paths scalloped by the hooves of long-dead pack horses point us north through dozy river towns and hamlets of geriatric farmers. Local place names contain characters for the words yi (post station) and pu (market station), suggesting waypoints along a great, dissolving road system of antiquity.

At Sword Gate Pass, we climb a Shu kingdom fortress so famed it has spawned its own Chinese proverb: “One man at the pass keeps 10,000 at bay.” Standing at the summit, I scan the green hills once again for telltale lines of cypresses, knowing that the world they once shaded came undone a century or more ago because no fierce battlements could keep out the whine of a car, or the thin wire of the telegraph.