why do they have arranged marriages?

Here are some reasons, i think may help you understand this. First of all, women belongs to men in the patrilineal society. Girls usually stayed at home before they get marriend. Their parents, especially father, will decided who they are going to be married according to the rule: Two related families united by marriage of equal status or prestige. In ancient time, people's life span was short, so girls usually got married at a young age, generally 16. Their partner had been decided 1-2 years ago, or even earlier. The habit of binding the feet had been in China for a thousand years old till the Ming and Qing Dynasty, although there is no acurate evidence showing which year it began. With small binded feet, women were confined to their boudoirs.