Not like Stone Age primitive, but more in the sense of their ships not being as good as the prophets or the other races, using swords more than guns, stuff like that

When the San'Shyuum first encountered the Sangheili, they had developed slipspace engines, established multiple colonies, and utilized plasma technology for weapons and power sources. As the war progressed, their technology only became more advanced as secret groups of Sangheili emerged, revealing that they've been studying Forerunner technology in the shadows for centuries. Known Sangheili culture has a strong emphasis on sword usage, but not to the point where it is their primary weapon.