Sweden concentrated on finding its appropriation of land known by the name "Ingermanland" in early sixteenth century. That allowed Sweden to complete a land bridge between Estonia and Finland, and bring the whole coast of the Gulf of Finland under Swedish occupation.
The Swedish reason was to establish a bridge between Estonia and Finland to unify the entire Gulf of Finland under the Swedish Viking power.
The Livonian War of the mid-sixteenth century was victorious for the Swedes and therefore occupied the territory of Ingermanland. Later it was returned to Russia by the Treaty of Teusina, also called "The Eternal Peace with Sweden" between the Russian and Swedish empires, respectively. But in 1610, war broke out again and both empires began hostilies which have been known as the "Ingriana War". The result was a Swedish victory, and the expulsion of the Russians.
After the war, Sweden achieved its objectives through Stolbovo Treaty, signed on February 27, 1617 between Russia and Sweden. The Province Ingermanland with the peoples of Ivangorod, Jama, Koorye and Nöteborg came under Swedish rule. The so-called countries Ingrians as slottslän returned to Sweden. In Norse, the Isthmus of Karelia, Kexholm län, Priozersk and Vyborg län. Sweden built stone fortresses in each of these centers to prevent further Russian incursions.