I agree that this is not something a empire would do if they were civilized

I agree that this would be a great claim the use in a DBQ like environment

How many wars/fights did they use these biological warfare tactics in?

Zhao Bing

The Mongol general Bayan was bent on eliminating the threat posed by Song remnants, so he led his troops in pursuit and attacked southern China. He was forced to flee in order not to be killed due to mass murder of the song dynasty

Mongols and merchant caravans that were poorly quarantined and underreported by the Mongol government inadvertently brought the plague from central Asia to the Middle East and Europe.

They took out babies from their mother before the child was actually "born"

Ghengis Khan even setup a messenger system which improved communication within his empire

They had strict laws against bodily harm, thievery and murder as well.

They promoted diversified economic development. They built canals for trade, were patrons of the arts, and even created tax free customs zones protected by the Pax Mongolia

When the conquered lands they did so by driving all the people out of the land and killing them. No one left alive