938 B.C.E. was the year the San'Shyuum first encountered the Sangheili on Sanghelios. The Sangheili believed that Forerunner artifacts were to be worshiped, not messed with. This resulted in an all out war between the Sangheili and San'Shyuum. The Sangheili were superior on the battlefield; the San'Shyuum were superior in space engagements.