Beyond their monumental size, earth buildings are unique for their jaw-droopingly robust architecture. Essentially castles or fortified villages, the multi-storey earth buildings were erected with a mixture of earth, sand, lime, glutinous rice, bamboo and wood chips, stoutly tamped into coffee-coloured walls up to two meters thick. They would expect a hammering in times of discord, so sturdiness was essential. Each stronghold could shelter hundreds of people ?- all sharing the same surname - and if danger approached, the iron-sheeted solid wooden doors would be swiftly bolted shut and weapons distributed among the men. Food would be stockpiled in advance and water drawn from wells within the building, so sieges could be drawn-out affairs.

    The Hakka (in Mandarin: Kejia, meaning 'guest people') - who live in scattered pockets across south China  and speak their own dialect - originally migrated from a central region of China around 1500 years ago. The name ‘guest people’ suggests a tribe on the move, which was once the case, as the Hakka were continually displaced by war, persecution or famine.

    Old-timer earth buildings may date to the 12th century but the youngest were only built in the 20th century. In a typical earth building - such as Zhencheng Lou not far from the town of Hukeng in Yongding country - families live in rooms leading off from wooden galleries arranged over three to five levels in a ring-like formation, which face onto a circular central courtyard. Kitchens are all downstairs with living quarters and windows upstairs. Within the courtyard - itself open to the sky and rain, sunshine and starlight - further concentric rings and corridors contained ancestral shrines and halls, tucked away beneath tiled roofs. The bulky walls keep the earth buildings warm in winter and cool in summer, or so locals attest. At harvest time, persimmons are everywhere, drying in the sun.