Complex sentence: Britain was concerned that Russia would take advantage of Chinese weakness in policing the area to gain territory, and in 1893 reached agreement with Russia to demarcate the rest of the border, a process completed in 1895.
Split into simpler sentences: Britain was concerned that Russia would take advantage of Chinese weakness in policing the area to gain territory. 'Tajikistan and the High Pamirs', Odyssey Books, p476 and in 1893 reached agreement with Russia to demarcate the rest of the border, a process completed in 1895.