The Talsh Empire is a very large country to the south of New Yogo, across the ocean from Sangal. The country is so large that it must constantly expand to keep its economy from collapsing. When the Talsh annex a state, that state becomes a puppet country under its own leadership, but now funneling people and resources to the Talsh. Old Yogo is one of the countries the Talsh have annexed.
The Talsh Empire is ruled by an Emperor with several adult sons, each of which controls his own region. Prince Raul, the second son of the Emperor at the time of the series, is eager to annex New Yogo, Sangal, and the surrounding countries in order to cement his claim on the throne. Hugo Arayutan is one of Prince Raul's agents, a Yogo citizen who joined the Talsh army after his country was overrun.
The capital of the Talsh Empire is Rahan, a very large and metropolitan city than astounds Chagum with its size and population when he visits. The Talsh Empire is itself so large that it makes New Yogo look extremely insignificant on Raul's map of the world.