In 1557, Bokhara and Khiva sent ambassadors to Ivan IV seeking permission to trade in Russia. Russia had an interest in establishing a trade route from Moscow to India. From then until the mid-19th century, Russian ambassadors to the region spent much of their time trying to free Russians who had been taken as slaves by the khanates. Russia would later expand across Siberia to the Far East, where it reached the Pacific port that would become known as Vladivostok by 1859. This eastward expansion was of no concern to the British Foreign Office because this area did not lie across any British trade routes or destinations, and therefore was of no interest to Britain. Beginning in the 1820s, Russian troops would begin to advance southward from Siberia in search of secure boundaries and reliable neighbors. This advance would not cease until Russia's frontiers and her sphere of influence were firm in the Central Asia, and this would include Bokhara and Khiva.