阅读理解。阅读下列短文, 从给的四个选项 (A、B、C和D) 中, 选出最佳选项。
According to historical documents, the forefathers of the Naxi people were closely related to a tribe called “Maoniu Yi” in the Han Dynasty，“Maoniu Yi” in the Jin Dynasty and “Moxie Yi” in the Tang Dynasty.
Between the early 10th century and the middle of the 13th century, production in the Lijiang area experienced marked changes, as agriculture replaced livestock (家畜)breeding as the main occupation of the people. Scores of agricultural, handicraft, mineral and livestock products were turned out, and the country presented a picture of prosperity. During that period, a number of slaveowning groups in Ninglang，Lijiang and Weixi counties gradually grew into a feudal manorial lord caste(世袭封建庄园领主制)．
