In 1677 the East India Company established an agency at Amoy, which, though withdrawn in 1681, was re-established in 1685. The first treaty with Russia was negotiated in 1679, but less than ten years later a further treaty was found necessary, under which it was agreed that the river Amur was to be the boundary-line between the two dominions, the Russians giving up possession of both banks. Thus Ya-k'o-sa, or Albazin, was ceded by Russia to China, and some of the inhabitants, who appear to have been either pure Russians or half-castes, were sent as prisoners to Peking, where religious instruction was provided for them according to the rules of the orthodox church. All the descendants of these Albazins probably perished in the destruction of the Russian college during the siege of the Legations in 1900. Punitive expeditions against Galdan and Arabtan carried the frontiers of the empire to the borders of Khokand and Badakshan, and to the confines of Tibet. Galdan was a khan of the Kalmucks, who succeeded in establishing his rule through nearly the whole of Turkestan, after attaining his position by the murder of a brother. He attacked the Khalkas, and thus incurred the resentment of K'ang Hsi, whose subjects they were; and in order to strengthen his power, he applied to the Dalai Lama for ordination, but was refused. He then feigned conversion to Mahometanism, though without attracting Mahometan sympathies. In 1689 the Emperor in person led an army against him, crossing the deadly desert of Gobi for this purpose. Finally, after a further expedition and a decisive defeat in 1693, Galdan became a fugitive, and died three years afterwards. He was succeeded as khan by his nephew, Arabtan, who soon took up the offensive against China. He invaded Tibet, and pillaged the monasteries as far as Lhasa; but was ultimately driven back by a Manchu army to Sungaria, where he was murdered in 1727. The question of the calendar early attracted attention under the reign of K'ang Hsi. After the capture of Peking in 1644, the Manchus had employed the Jesuit Father, Schaal, upon the Astronomical Board, an appointment which, owing to the jealousies aroused, very nearly cost him his life. What he taught was hardly superior to the astronomy then in vogue, which had been inherited from the Mongols, being nothing more than the old Ptolemaic system, already discarded in Europe. In 1669, a Flemish Jesuit Father from Courtrai, named Verbiest, was placed upon the Board, and was entrusted with the correction of the calendar according to more recent investigations.