Ottomans had an increasingly harder time keeping up with the industrial and military progress in Europe. This was undoubtedly proven in losses against the Russians, which culminated in the Treaty of Kucuk Kaynarca in present-day Bulgaria in 1774. In addition to losing the Crimean Tatar Khanate, the Ottomans had to give Russians the authority to interfere in their internal affairs with the Christian Orthodox subjects of the empire.