After Titus completed his conquest and destruction of Jerusalem in 70 C.E., he returned to a triumphal welcome in Rome, a city with 50,000 Jews and 11 synagogues.
He returned with thousands of Jewish prisoner-slaves, flooding and crashing the Roman slave market. (Many of these slaves were purchased and freed by Roman Jews.)
2 links for you below to two online articles on this topic.
On the destruction of the Temple
Wikipedia on Jewish demographics
