You're wrong, I quote from the Nestor chronicles, And justice was lost, tribe rose against tribe, great disorder and quarrels arose and they started to fight among themselves. And they said to one another: 'Let us find a Prince, who will rule over us and bring justice'. And they went back over the sea to the Varjags (Varidg). They were also called Russes, like others were called Swealanders, other Norrlanders, others Angles, others Gothtalanders. And they said to the Russes: 'Our land is big and wide, but without any order. Come and rule over us and be our Princes!' And three brothers were chosen from among them and they took all the Russes with them and came.  If anything is a profession it's Varjag. I confirm: Varjag is profession and Rus most likely tribe or clan. But back to Nestors chronicles. That same paragraf tells that those who asked Rus to became their prince were Chuds, Slavs, Krivitsian and Vepsian tribes. Chuds and Vepsian are finnic peoples, and Krivitsians was most likely Baltic tribe. So half of the founding tribes of Novgorod were Finnic and only 1/4 Slavic. This composition made this domain's governing system republican.