In the UNSC's begining, the UNSC had colonized many planets. One group of people attempt to colonize the outlying world of Helghan. However, the world is extremely desolate and the air scorches the colonists lungs. Also present in the atmosphere is heavy radiation, which causes the colonists' hair to fall out and their children to be born deformed; the average Helghan is taller than a normal human. In time, the colonists' bodies adapt, allowing them to breathe the caustic air. However, due to their unique adaptions the require distinctive specialized respirators when off-world and has lent them the epithet of "Bucketheads".
First Helghan War
Withthe helghasts view of a pro-human military and industry and corruption controlling politics, many poor Helghans blamed Humanity for the hardship they have endured and started the First Helghan War. After several years of war, Scolar Visari eventually emerged as leader and declared himself the first Emperor of the Helghast and started ethnic cleansing programs throughout the Helghan system.
Second Helghan War
By the year 2523, Eventually, Emperor Scolar Visari declared war on humanity, invading an UNSC planet called Vekta. The UNSC had built a number of defense platforms on several planets that were supposed to stop an advancing army from attacking or invading any planets and were supposed to be foolproof. But, with the help of mavericks, the platforms malfunctioned, leaving Vekta open to an attack from the Helghast.
But two years later, contact with the covenant made the helghasts a secondary priority.
By 2552, The emperor had joined the new consortium under the leadership of former maverick hunter sigma. helghast forces had been rapidly deployed across the UNSC territories.
Fall of the Empire
Two months after the consortiums and the covenant's uneasy alliance was formed, the covenant had broken the alliance when they assaulted helghan and glassed the planet. after that, the empire had ben broken to peices and the helghasts scattered.