China needs growing room and California is conveniently located. California already has a huge Asian population, so assimilation into China would be relatively easy. California would become the newest province of China. The People's Republic of China flag would fly proudly over all buildings...
At the individual level it's called, "getting married". Victims of marriage stop bar hopping (nomadic) in favor of boring nights at home turning into a mental vegetable (agricultural). Marriage is a form of slow death practiced by all civilizations.
This is the most thought provoking question that I've seen on YA. A good dill pickle is the key compliment to any sandwich, but how could we keep windows clean without squeegees? It's a tossup. They are both equally critical to human survival and happiness.