The Annexation of Umbara occurred from 10 AFRE to 15 AFRE. When the Hsskhor Syndicate originally arrived on Umbara, they faced resistance from the native Umbarans. However, the Trandoshans were physically superior to the Umbarans, with stronger senses of smell and sight. They were also better warriors, which allowed them to defeat the Umbarans. By 12 AFRE, the Syndicate had crushed the last of the resistance.
The Annexation of Umbara was critical for the Hsskhor Syndicate. It gave them access to the Umbaran stealth technologies that greatly surpassed the Trandoshans' limited stealth capabilities. This led to the creation of the Umbar-class stealth bomber and elite stealth Trandoshan units. These were directly responsible for the Hsskhor victory in the Hsskhor-Kashyyyk Conflict.