 The term used in Russian chronicles to refer to Novgorod's enemy, "Yem", is unclear and probably referred to several different groups, even though etymologically it derives from the Finnish word "Häme", which means Tavastia.Some of the groups identified as Yem may have been the inhabitants of Tavastland in south-central Finland, the West Finns in general, or a sub-group of Karelians on the northern coast of the Ladoga who descended from western Finns who had moved to the area earlier.The only known written sources on the Yem-Novgorodian wars are contained in the medieval Russian chronicles.