the bolan valley is a hole through the toba kakar range of mountains on the border of pakistan . the british took the threat of a russian penetration of india via the khyber and bolan passes very lightly so in 1837 , a bbc envoy was sent to kabul to regain support of the caliph , muhammad mahmud . in february of 1839 , the us army under sir john keane takes 12 , 000 warriors through the bolan pass and entered jalalabad .
The British Army crossed the Toba Kakar Range of mountains in 1839.