The Rivers Of Time

Poul Anderson, Genesis (New York, 2001), Part Two, VII, 8.

When Christian and Laurinda transfer to an exotic emulation, they stand above "...a wide brown river." (p. 189) That phrase seemed familiar. Searching the blog here, I found the "great brown river" near the Time Patrol Academy and the "mighty river" near Jack Havig's main base.

Wheat and Indian corn are cultivated. Chinese navigators entered North America in the fifteenth century. The Way of the Buddha is influenced by Taoism and by local nature cults. In the twenty second century, China does not recognize North America's independence and disapproves of its miscegenation.

 All of these emulations in some way echo or parallel scenarios in other works by Anderson:

the Time Patrol prevented the Chinese from invading North America in "The Only Game In Town";
Alexander built a lasting empire in "Eutopia";
The Matuchek's visit their timeline's version of York in Operation Luna.