The Taefemach

The Taefemach is a large region in eastern Rhydain, centered on the River Helvander and its valley. "The Taefemach" and "The Helvander Valley" are often used interchangeably, but to be precise, the Taefemach refers to not just the river valley itself but some of the surrounding uplands and smaller tributary valleys. The term "Helvanderûn" is also not precisely interchangeable, referring specifically to the bottomland directly around the Helvander, or to the flood plain or riparian lowland covering the floor of its valley. 
The exact territorial extent of the Taefemach is in fact up for debate, since as a culturally defined region, certain areas are considered part of the Taefemach by some but not by others. It is generally agreed that the main ranges of the Adhemars are not part of the Taefemach and instead mark its northern boundary; however, its southern and western extents are less clearly agreed upon. Some would consider the Lokenmoor, the northern flanks of the Helgremars, and the western shoulderlands of the Tythian Massif (and/or the Mountains of the Morn) to be part of the Taefemach; others would disagree on some or all counts and say those lands properly lie within Alondria, Rhyndara, or Tythium, respectively. 
Today, the central and eastern Taefemach forms the heartland of the Helvandrian League, with most of the League states lying at least partially within it. The kingdom of Gundarra is the other major state in the region, occupying the higher upland-and-valley terrain of the western Taefemach. In centuries past, the Taefemach was part of the core provinces of the Old Empire, and before that, it was mostly subject to the dominion of Qoss.