They were forced to leave Earth after loosing a battle against Reptoids in ancient India (date unknown), which they had been visiting for around 200 years.
They have resumed their visits to Earth in 1948.
Technologically this is a very advanced race.
Their ships are often invisible (to radar and the Human eye) and they wear some sort of clothing that makes them invisible as well.
Supposedly they come from Jupiter or from one of its moons.
Last sighting: Portugal, May 2005.