evidence: East meeting West, North meeting South: since time immemorial, the Wakhan Valley, in the Pamir Mountains, has existed at the intersection of trails trodden by nomads, peddlers, pilgrims and, at times, the soldiers and emissaries of great powers. When I’d thought about traveling to see this rugged branch of the ancient Silk Road, it had seemed like an adventure to the far-flung periphery of the world. Now, as I looked around the market, taking the long view of history, it felt more like the center. [...] After the three legs of my flight from New York, armed with a visa and special permit to visit the Pamir region, I arrived in Dushanbe during a stifling week last July. The Russians gave the city a rail link west to Uzbekistan, and they paved a road east, toward Kyrgyzstan, that is known today as the Pamir Highway and increasingly draws foreign mountain bikers and motorcyclists.