Around the world and beginning in the 1830s in the u.s. the growth accelerated "during the <span>industrial Revolution". This revolution made the incomes of most social classes except the elite soar in ways they had not before, creating upward mobility.</span>
It was Spain due to that it was controlled by the many Muslim Caliphates but the Reconquista end those 800 years of Muslim population in Spain
Answer:
The primary purpose was, to protect the Chinese Empire from the Mongolians and other invaders.
