Yanshi is 10 times larger than Vallejo, California.
Area: 89 km2 calculated
Vallejo is the largest city in Solano County, California, United States. The population was 115,942 at the 2010 census. It is the tenth most populous city in the San Francisco Bay Area, and is located on the northeastern shore of San Pablo Bay. Vallejo is named for General Mariano Guadalupe Vallejo. Wikipedia
Area: 933 km2 calculated
Yanshi is a county-level city administered by the prefecture-level city of Luoyang in western Henan province in the People's Republic of China. Yanshi lies on the Luo River. Erlitou, the main site of the eponymous culture, was discovered here in 1959. Wikipedia