The Anesa river (Mirselec Anesa ainos) is a river in the south of Masalne, and a tributary of the Rushalya. Sometimes it is also known as the "Border River" (Mirslec Gaeste ainos), for two reasons: firstly it is analogous to the Border Ridge, with which it forms the dividing line of the Feladmena Plain which it flows through; and secondly, for a significant part of its course, it forms the border between Eonis and Inezama Province.
The Anesa river's source is in Lake Inomi, one of the few lowland lakes of Masalne, situated in Inezama Province. From there it first veers north, and the northwest; this is when it is known as Gaeste ainos. At the intersection of the two provinces with Feladmena Province, the river continues flowing northwest and then bends west until it meets the Rushalya river; the confluence is the site of the city of Ainemorne. In total its length is about 166 km.
The Anesa is one of the first rivers on the island to have had humans reside along its banks. As early as 5,000 BDN the riverbanks are dotted with villages, and by the time of the first kingdoms in Masalne the valley of the Anesa river was the heart of the Anesa Kingdom, which commanded all the territory analogous to modern day Ostema, Eonis and Inezama provinces. This was one of the most powerful of all the kingdoms, and was a direct rival and enemy of the Sanose Kingdom farther north, based in the Feladmena Plain. The third and fourth centuries BDN, known in Risevne as the Era of the Kingdoms, was dominated by the struggle between these and other early kingdoms in the south of Masalne, and the river was the site of many forts and naval battles in wartime, while becoming a large highway of people and goods during times of temporary peace.