Home to the Thanagarians, a race of avian warriors.
Thanagar was a relatively young culture with limited spaceflight as of 16,000 BCE, and distantly related to the Shi'ar.
Thanagar might not have merited any special attention except for three reasons: Thanagar was located relatively close to Asgard geographically; it was a culture with a strong military tradition and warlike demeanour; and they possessed a rare, unique alloy called 'Nth-Metal'. Capable of many remarkable properties, it was primarily useful as a tool for negating magic. Though nowhere near as strong as a single Asgardian, the Thanagar 'Hawkmen' were still excellent fighters and their weapons caused real harm. Their warlike nature made conflict inevitable and helped stall the Asgardian expansion by several hundred years.