Protendren

Prior to the establishment of Endref, many of the creatures and humanoids who now reside in Tsrach lived in what is now northern Endref. These communities, unconnected and individualistic as they were, had a common language and written system that is now often referred to as Protoendren. Though no in Endref speaks protoendren, there are some who claim that many of the humanoids who live in Tsrach now speak a language derived from protoendren, if not a devolution of the language as those humanoids have become more wild and less connected to the broader world.
The spoken component of the protoendren language is not well understood, and many inferences have been made based on very rough study of current Tsrachian language. Based on that analysis, protoendren is thought to have been "coarse-sounding", with a good deal of glottal and throat sounds combined with teeth clipping and tongue-based sounds. 
The written component of protoendren is slightly more understood, largely due to some limited samples being discovered either in Tsrachian cave systems which were raided (by mercenary companies of Endref merchant forces) or in abandoned sites in northern Endref. The written language appears to use a combination of 35 different symbols to make up more complex series of symbols, generally more aligned with semi-pictographic representations rather than sentences. The marks used to make these 35 symbols were all based on combinations of one to five strokes conducted simultaneously, mostly likely by deft claw movements on soft surfaces such as mud, clay, wet wood, or hide. There strokes could very easily be mistaken for random scratchings, but persistent study has shown similarities that make it more akin to other known languages. 
Some mages in the north of Endref have undertaken a systematic study of the protoendren language, based out of the Floating Coin. Through their work thus far, they have discovered most of what is known in "civilised" nations about protoendren, although several trips into Tsrach to attempt to learn more have resulted in nearly catastrophic injuries for the exploring parties.