After the riots, I get tea for 40 cents a mug in Old Sanaa. Mocha is a town in Yemen, but that doesn't mean the coffee here is any good. The teahouse is along the sunken road that girds the historic center. People will tell you that Sanaa is the world's first city, founded by a son of Noah where the Arabian Peninsula's highest mountains emerged from the Flood, and certainly it does look old and muddy. At its heart is a magic quarter of ancient history—a mud Manhattan of tower houses of brick and quartz, up to seven stories tall, lording their pre-industrial height over a labyrinth of dense lanes. Everything is uniform, even its mazelike impenetrability and gaudy decorations, more gingerbread than Arab. Old Sanaa looks more baked than built.

The old man at the tea shop has black stumps for fingers, from years of working over a roaring gas ring, and he brews like a man obsessed, raising and lowering a tiny spittoon of black tea until it froths just so, dribbling in condensed milk, then adding a heap of Brazilian sugar that caramelizes in the pot. The result is fantastic—cardamom and tannins, stirred in the Middle Ages, sweetened over fire, a rare vice in one of the world's driest towns.

Contented men sit in rows outside the shop, fingering their worry beads. Their great bellies, encased in white Arab thobe robes, are girded by extravagant belts and pricked by enormous jambiyas, curved daggers the size of pizza slices. At my request, they take out the knives. All the flash is in the handles, once made of rhino horns, now steel and braided with gold thread and decorated with coins. Like Yemen itself, the blade is of inexpensive material but sharp. "Blood groove," says a gentle, scholarly-looking Yemeni at the next table, sliding a finger down the blade. "So you can pull it out easy, stab him again." Men wear knives always and everywhere—to weddings, business meetings, tea shops. They look like a row of Pillsbury assassins.

If you are patient, like a Yemeni, you won't burn your fingers on the metal mug. Or your tongue on the contents.

YEMEN MEANS "SOUTH," according to legend, if not dictionaries. Caravans loading up on incense used to arrive at Sanaa's Bab al Yemen, or, loosely, Gate of the South. The country sits at the bottom of the Arabian Peninsula, a mountainous, 1,200-mile-long strip pressed upon from north and east by Saudi Arabia and Oman, its west coast facing Africa across the Red Sea and its long southern one looking out on the Gulf of Aden toward Somalia and the Indian Ocean beyond. Nearly all of Arabia's 10,000-foot peaks are in western Yemen; the low Empty Quarter, the Rub' al-Khali desert, begins in the east. Shiite rebels fight in the north, secular secessionists in the south. Tribes are everywhere, and Al Qaeda somewhere. It is the most miserably poor of the Arab nations, heavily illiterate, and full of the resulting graces—hospitality, tradition, a deeply conservative pride. It has one foot in the medieval world and the other in antiquity.

The appeals of such a setting cannot be described, only felt. Yemen has always been waq al waq, beyond the beyond, a phantasm where men chew leaves and camels live on fish. From the dunes of the Empty Quarter to some 200 islands, everything about Yemen is mystery, legend, or myth. It takes a bold traveler to visit, but the rewards are high and the door open—sometimes. Even esoteric Socotra Island, the source of frankincense and myrrh for the ancients, described by Marco Polo, turns out to be a real place, 200 miles into the Indian Ocean, a Galápagos of the Arab world with 6,000 visitors a year and daily flights. In the midst of revolution, all over a country very much in play, I meet Czech trekkers, German shutterbugs, and Italian beach snobs all willing to risk Yemen in order to see Yemen. Last May, the country actually launched a tourism offensive, opening its coastline for resorts like those up the Red Sea at Egypt's Sharm el-Sheikh—vacations in the ancestral home of the bin Ladens.

Beautiful, amazing, dark. After you've seen the fortresses (cute but small) and ancient cities (Syria has more), travel in Yemen is travel through time itself. Nowhere is less now than here. "The most amazing trip of my life," the novelist Annie Dillard told me when I said I was planning to go, adding, "but they are going to kill you in a second." Intending to measure the country's tourism potential and natural conditions, I landed in the middle of a revolution. Revolution, it turns out, is the natural condition of Yemen.

YEMEN IS PURE, SORT OF. There is no McDonald's, although there is a KFC. The houses, social mores, modes of dress, and allotment of time all follow classical patterns; baseball caps are rare because they interfere with bowing for prayer. Yemenis claim that their versions of Arabic and Islam are among the least diluted in the world.