9 of the states had to agree before a law was passed.
Its spread mainly because of the pest rats and also fleas
Because of the need for water and other resources. Central Australia is mainly desert, and has a hot, dry climate.
Prior to the existence of the nation-state, Europe was comprised of several multi ethnic empires, the largest and most powerful of which was the Holy Roman Empire. Territory changed hands often. Many times, this took place because of marriage or as a result of war.
Challenges for growing crops are you don't know if it will be successful, you have to have enough water, the dirt has to be fertile, and the weather may affect how the plant grows.
