The oldest precursors of the luopan are the or , meaning "astrolabe" or "diviner's board"—also sometimes called "liuren" astrolabes—unearthed from tombs that date between 278 BCE and 209 BCE. These astrolabes consist of a lacquered, two-sided board with astronomical sightlines. Along with divination for Da Liu Ren the boards were commonly used to chart the motion of Taiyi through the nine palaces. The markings are virtually unchanged from the "shi" to the first magnetic compasses. The schematic of earth plate, heaven plate, and grid lines is part of the "two cords and four hooks" () geometrical diagram in use since at least the Warring States period.