The Russia into which the Tsarevich Peter was born in 1672, and of which he became joint ruler ten years later, was a poor, thinly populated and backward country. She had few towns of any size, no large-scale industry; her economic life was based on the production of timber, furs and salt, and on an inefficient agriculture. Vast areas were still undeveloped and virtually uninhabited. The only direct geographical outlet to the West was the port of Archangel, frozen for half the year; from the Baltic Russia was severed by Sweden's possession of Finland, Ingria, Estonia and Livonia; her frontiers were as yet several hundred miles from the Black Sea, the Crimea being a tributary state of the Ottoman empire and the raids of its Tatar inhabitants still a serious menace to the security of south Russia and the Ukraine. From the second half of the fifteenth century, however, soldiers, doctors and skilled workers of many kinds from western Europe had been active in Russia, and western ideas and techniques slowly taking root there. In the, seventeenth century this process was accelerating, but even in its last decades Russia was far from being a part of Europe in any true sense. She was isolated not merely by geography but also by her distinctive and in many respects unfortunate history, by a national pride so intense and arrogant as to attract the comment of almost all foreign visitors, and above all by deep-rooted religious differences. The Orthodox Church, her wealthiest and most powerful institution, had inherited from Byzantium a profound feeling of superiority to western Christendom and was in general a most formidable opponent of foreign influence.