The Years of Rice and Salt, by Kim Stanley Robinson

This book starts with the bubonic plague. It has essentially decimated Europe in the 14th century (A.D.), killing off almost everyone on the continent and allowing Asia to become dominant instead of Europe. China and the Middle East, and to a lesser extent India, become the superpowers, and eventually even the "New World" is allowed a seat at the global table.

Very interesting. The last couple of chapters were a bit meh, but the religious, political and scientific discussions of the rest of the book were fascinating.