Well, I suggest you that you need to check the" human-forerunner war" in Halopedia. To be short, the name you mention above is the capital planet of the human empire,which was captured after a 53-year long battle between the warrior-servant led by the diadact and the human forces. The reason why they didn't communicate was clear,in my opinion. Because from the very beginning,when the floods invaded,they expanded for survival and thus resulting in the total conflict between human and forerunner. If they looking for help,they would have to accept the forerunner as their savior and ally,and eventually lose controlwith thepower,which could lead to their destruction overall.

Well, I suggest you that you need to check the "human-forerunner war" in Halopedia. To be short, the name you mention above is the capital planet of the human empire, which was captured after a 53-year long battle between the warrior-servant led by the Didact and the human forces. The reason why they didn't communicate was clear, in my opinion. Because from the very beginning, when the floods invaded, they expanded for survival and thus resulting in the total conflict between human and forerunner. If they were looking for help, they would have to accept the forerunner as their savior and ally, and eventually lose control with the power, which could lead to their overall destruction.