Before the first half of the 20th century, almost all of the residents from the mountainous areas in Nanjing County, Fujian Province of China, lived in traditional earthen buildings known as tulou. The tulou were built by the Hakka and Han people and some are more than 500-years-old.
A tulou is a large, enclosed and fortified Chinese rural dwelling whose walls are made of rammed earth, cobblestones and bamboo sticks. They were built at a time when bandits and wild animals roamed the remote mountainous countryside freely, hence defensive structures were required to keep the locals out of danger.