42707
Dikes and irrigation in Ningxia trace to the beginning of dynastic rule , when the Qin rulers who unified China in 221 B.C. built irrigation for soldiers garrisoned on some of the earliest sections of the Great Wall .
 Ningxia, China; China, Ningxia; China, Ningxia
Please list all entity pairs containing a certain relationship in the given options.Output format is "word1, word2; word3, word4". 
Option: ethnicity, place lived, geographic distribution, company industry, country of administrative divisions, administrative division of country, location contains, person of company, profession, ethnicity of people, company shareholder among major shareholders, sports team of location, religion, neighborhood of, company major shareholders, place of death, nationality, children, company founders, company founded place, country of capital, company advisors, sports team location of teams, place of birth 
Text: {0} 
Answer:
 Ningxia, China; China, Ningxia; China, Ningxia