Chokhor Raptse Dzong, more commonly known simply as Trongsa Dzong, was built in 1644-1647 and used to serve as the seat of power for the Wangchuck dynasty prior to its ascension to rulers of Bhutan in 1907. It is the largest dzong fortress in Bhutan, built on a spur that overlooks the gorge of the Mangde Chhu (river). Trongsa Dzong controls east-west trade, with the precursor of the modern Lateral Road, the only road connecting eastern and western Bhutan, passing through the dzong's courtyard. This allowed its rulers, the Wangchuck dynasty who initially were the penlops (governors) of the region, to close its great doors and effectively divide the country in two if they so wished.