Passage: The northern and central part of the peninsula is partially inhabited by the Sami, often referred to as "Lapps" or "Laplanders," who began to arrive several thousand years after the Scandinavian Peninsula had already been inhabited in the south. In the earliest recorded periods they occupied the arctic and subarctic regions as well as the central part of the peninsula as far south as Dalarna, Sweden. They speak the Sami language, a non-Indo-European language of the Uralic family which is related to Finnish and Estonian. The first inhabitants of the peninsula were the Norwegians on the west coast of Norway, the Danes in what is now southern and western Sweden and southeastern Norway, the Svear in the region around Mälaren as well as a large portion of the present day eastern seacoast of Sweden and the Geats in Västergötland and Östergötland. These peoples spoke closely related dialects of an Indo-European language, Old Norse. Although political boundaries have shifted, descendants of these peoples still are the dominant populations in the peninsula in the early 21st century.

Question: What was their language similar to?
Old Norse