With lunch came several cups of tea that, geographically speaking, were the start of one long tea-drinking session. (I would not encounter coffee again until Istanbul.) I drank tea on the train from Hong Kong to Beijing, where each compartment is supplied with a thermos of hot water but nothing in the way of actual tea leaves. (I had to mooch, via hand gestures, from a fellow passenger.) I drank tea at Beijing's Fu Jia Lou Restaurant, where, just as I was recovering from ingesting the spiciest cabbage in existence, a fistfight broke out. (In 80 days and nearly a dozen countries, it would be the only instance of violence.) I drank tea in a dusty, near-forgotten village called Water's Head, not far from where I had hiked a deserted stretch of the Great Wall (most people visit the aforementioned Badaling). There are no hotels in Water's Head, so my guide, an American named David Spindler, had arranged for us to spend the night with a local family, on a communal bed known as a kang. As I unfurled my state-of-the-art sleeping bag, Grandfather Han, the family patriarch, was dumbfounded to the point of giddiness by the very sight of it. Reaching out, he rubbed the tangerine nylon between his fingers, broke into a disbelieving laugh, and then shut off the light and went to sleep. That night was the most memorable of my trip. But whereas my second most memorable—at the Vigilius Mountain Resort, a masterpiece of contemporary architecture in Italy's South Tyrol—ran $604.25, my night at Water's Head cost just $13.09. Including tea.

I also drank tea in Mongolia, which is a true border culture. If you order a bowl of noodles in Ulaanbaatar, you're as likely to be handed a fork as you are a set of chopsticks. The steamed dumplings, furthermore, have the look and feel of dim sum but taste more like pierogi. When it comes to hot beverages, however, Mongolia is squarely in the tea-drinking camp. The people there prefer it with goat's milk and salt, and they call it suutei tsai.

I drank my first cup of suutei tsai in a circular cotton-and-felt tent known as a ger. I had just spent the day visiting the town of Kharkhorin, which is slated to replace Ulaanbaatar as Mongolia's capital in the year 2020, though today it is very much a crossroads. Desert nomads pull up to the open-air market on horseback to buy everything from plastic buckets to Chinese motorcycles. The ger belonged to a man named Batkhu, and his mother served me the suutei tsai along with a biscuit made from dried milk curd. Later, I found myself standing outside Batkhu's ger, watching as he slaughtered a sheep in the traditional Mongolian manner. He made an incision just below the rib cage, inserted his hand and then his entire forearm into the animal's abdomen, punched through the diaphragm into the chest cavity, and pulled the sheep's veins away from its heart, at which point the sheep closed its eyes and drifted into nonexistence.