Mars served as a fright god Phobos to his father Ares during the Earth’s Greek times. He planned on killing Ares, and take his throne, but was betrayed by his own brother. Phobos escaped to Rome and took the name Mars and ruled as a god of War. This again took him into conflict with his father. Ares defeated Mars and banished his to a planet Kar’tek.
On Kar’tek they found an alien race, the Volca. However, their physiology was not suited to carry the Goa’uld symbiote. However the beasts of this planet were able to bear the symbiote, and Mars was eventually forced to swap his host to that of Mar’kak. He then built himself and his Jaffa mechanical bodies to protect the feeble hosts.