Son of King Anga and Sunitha, the daughter of Mrityu, the death.
When Vena became king, not only did he let the kingdom deteriorate, he forbade fire sacrifices. The sages spoke mighty mantras, Vena died. Then they kneaded the dark out of his body, as they continued to knead the light appeared in the form of Prithu. Prithu became king. He cultivated the earth.
The earth was named Prithivi after him.
Some myths say, a dark being came out, which they called Nishada and is considered to be the progenitor of the Nishadas.
For the story visit
http://hindumythologyforgennext.blogspot.com/2013/11/prithvi.html