Glacial Maximum. Y90K.BC.
The Boreal season, was a warm season shortly after the end of the last Ice Age about 10500 to 8000 years ago, the early Holocene glacial ice sheet melted away from Europe. The weather was dry and warm. The temperature was pretty close to the present. In this case, the Nordic countries were a spread of mixed forests, which were made of birch and pine. Pine became common in the Central Lapland. The Boreal period was much drier in southern parts of Finland at the end of the period it was up to 1 degree warmer than the present, and it produced warmer climate species of flora plants.
Viking Age is the term for the period in European history, especially Northern European and Scandinavian history, spanning the late 8th to 11th centuries. Scandinavian (Norse) Vikings explored Europe by its oceans and rivers through trade and warfare. The Vikings also reached Iceland, Greenland, Newfoundland, and Anatolia. Additionally, there is evidence to support the Vinland legend that Vikings reached farther south to the North American continent. (Wikipedia, Norse)
Norsemen is used to refer to the group of people as a whole who spoke what is now called the Old Norse language belonging to the North Germanic branch of Indo-European languages, especially Norwegian, Icelandic, Faroese, Swedish and Danish in their earlier forms. (Wikipedia, Norsemen).
It was during the Viking era that the significance of the Karelia Isthmus in the Baltic Sea and the lake Ladoga area grew. As the industrial commerce of weapons, tools and goods increased the abundance commerce increased. People from the west of Finland also wanted to take part in the increasing East trade.
People also from Karelia and from the Inkeri community went with the Vikings Eastwards as the interest in the traffic route grew. The Karelian journey Eastward was most likely during the Vikings trading, like a commerce road East wards, along the south of Lake Ladoga and south-eastern side of the trade centers.
The ancient Karelian heyday occurred in the Crusade period 1100 to 1200 AD. Population growth and prosperity based on the development of agriculture. During the Crusade periods, the Karelian core area consisted of the area downstream from the Vuoksi River, it is part of the Karelian Isthmus and Ladoga northwest and north coast.
According to the earliest East Slavic record, the Primary Chronicle, the Rus' was a group of Varangians among others like Swedes and Gutes who lived on the other side of the Baltic Sea, in Scandinavia and as far as the land of English and French.
The Varangians were first expelled, then invited to rule the warring Slavic and Finnic tribes of Novgorod:
“The four tribes who had been forced to pay tribute to the Varangians — Chuds, Slavs, Merians, and Krivichs drove the Varangians back beyond the sea, refused to pay them further tribute, and set out to govern themselves. But there was no law among them, and tribe rose against tribe. Discord thus ensued among them, and they began to war one against the other. They said to themselves, "Let us seek a prince who may rule over us, and judge us according to custom". Thus, they went overseas to the Varangians, to the Rus. These particular Varangians were known as Rus, just as some are called Gutes, and others Normans and Angles, and still others Gutes, for they were thus named. The Chuds, the Slavs, the Krivichs and the Veps then said to the Rus, "Our land is great and rich, but there is no order in it. Come reign as princes, rule over us". Three brothers, with their kinfolk, were selected. They brought with them all the Rus and migrated”. (Forbes., 1914).
Inkeri Land, Amazon Kindle Ebook.