The odometer was used also in subsequent periods of Chinese history. In the historical text of the "Jin Shu" (635 AD), the oldest part of the compiled text, the book known as the "Cui Bao" (c. 300 AD), recorded the use of the odometer, providing description (attributing it to the Western Han era, from 202 BC–9 AD). The passage in the "Jin Shu" expanded upon this, explaining that it took a similar form to the mechanical device of the south-pointing chariot invented by Ma Jun (200–265, see also differential gear). As recorded in the "Song Shi" of the Song Dynasty (960-1279 AD), the odometer and south-pointing chariot were combined into one wheeled device by engineers of the 9th century, 11th century, and 12th century. The "Sunzi Suanjing" (Master Sun's Mathematical Manual), dated from the 3rd century to 5th century, presented a mathematical problem for students involving the odometer. It involved a given distance between two cities, the small distance needed for one rotation of the carriage's wheel, and the posed question of how many rotations the wheels would have in all if the carriage was to travel between point A and B.