Astride the banks of the Yenisei River in the city of Kizil, capital of the Soviet Autonomous Republic of Tuva, stands a monument whose trilingual plaque in English, Russian and Tuvan, a Siberian Turkic language, announces its location as "The Center of Asia." Local legend has it that at the end of the 19th c;entury an errant Englishman, having already visited the centers of Europe, Australia and Africa, set out to add the center of Asia to his conquests. His compass led him to the Yenisei—not, in fact, to the site of the present monument, which was erected not long ago to complete a pleasant riparian park, but to a spot downriver on the ...