The Eastern Lands is a term that refers to the regions stretching from Tortall eastward and northward. Countries that are part of the Eastern Lands include Galla, Tyra, Tusaine, Maren and even Scanra. Tortall, Tusaine, and Maren are very culturally similar. Common is the primary language spoken throughout the Eastern Lands.
The governments of most of these countries are formed on the basis of the Code of Ten. The Eastern Lands are different from other countries, like the Southern Lands or Copper Isles, because they aren't slaveholding countries. Some, like Tortall, have allowed slaves in the past but have abolished it since. The main reason for this is that holding slaves isn't economical in those lands. There aren't that many big farms or a long-term slave economy so it would pay off. Scanra allows slaves and Maren has a bond servitude on the big farms which comes close to slavery.