During this period, the hydrologist Lǐ Bīng planned an irrigation system in the Mín Valley (10[1])called the Dūjiāngyàn. During a siege around the start of this period, the diversion of the Fén River forced the people of Jīnyáng to live on top of their houses. Perhaps the oldest known multiplication tables were found on bamboo strips from a tomb dating to this period. An attack during this period inspired the phrase “Besiege Wèi to rescue Zhào.” During this period, the philosopher Mèngzǐ (“MUNG-dzih”) taught at the Jìxià (“jee-sh’yah”) Academy. A text of strategies composed around the transition into this period, which some mark by the Partition of Jīn, is attributed to an earlier period’s general Sun Tzu. For 10 points, identify this period named for polities like Yān (“yen”) and Chǔ that came after the Spring and Autumn Period and ended with unification under the Qín ■END■