From the Jewish Talmud:
Sanhedrin 55b:

A Jew may marry a three year old girl (specifically three years ‘and a day’ old). 

Was this ‘a thing?’ And if it was, when did it stop, or is it still going? 

Curious 

The Babylonian Talmud is a central text of the Jewish tradition, and it is a compilation of rabbinical discussions, debates, and interpretations of Jewish law and tradition.