South Asia has traditionally followed a system of social ranking much like Indias caste system up until around modern day (roughly the 1940's) when many socialist and community governments were formed, such as the peoples republic of China, etc. This ranking system made it disgraceful to marry below your social status, and served to preserve culture as well as trade work from generation to generation. You could, sometimes, marry a bit above or below your station, but nothing drastic.

Families would arrange marriages to ensure that 1, their child never married too far outside their social ranking. 2, to make sure their kids had someone to marry. The deeper reason behind this varied by gender. Females were often primarily housewives and regardless of how they helped, seen as less valuable and more of a drain on resources compared to men. Women needed to be married so their fathers and brothers didn't have to take care of/ provide for them forever, and could instead start their own families or focus on their own wellbeing. Males on the other hand were expected to take care of their parents when they were no longer able to take care of themselves. In exchange for learning their family trade, skill, or inheriting farmland, the boys would make sure their parents were taken care of in retirement. This means marring to have some one help with their care while the son was away, as well as someone to start a new family with to ensure the cycle would continue when their child was older.

In a society where family depended so heavily on one another, it was a good idea to have a plan in place. This also served to guarantee that if the child grew and was, for whatever reason, undesirable, (I.E. injury or illness) they would still have a match waiting for them. This practice was later amended to wait until both parties were of marring age, and then called "matchmaking". The amendment was due mostly to loss of life in wars, changes in culture, and takeovers from outsiders to native lands.

Matchmaking remainded popular however as traditionally the sexes did not mix in polite society. Men and women might be seen walking down the same streets, but it was considered rude or even vulgar to speak to a stranger of the opposite sex. This is mostly due to the social ranking system referenced earlier. It could sometimes be hard to tell what social circle someone was in as travel became the norm and different cultural influences mixed.

What finally did away with this strange and brutal cycle was basically WWII. After the war many Asian countries had suffered, and had been suffering, from either bad dictatorships, invasion, famine, or exploitation from "whiter" countries. Revolution came and many societies overhauled their rules, including many of the lower social circles and barriers that their grandparents had previously honored. As the saying goes, "suffering makes all men equal when they suffer equally." And it held true. Outside influence and revolution changed the south Asian social landscape forever.

Today, South Asia is not the world capital of arranged marriages. Though some do take place, most marriages are not arranged by the couples parents beforehand. This does not mean that parents have stopped trying to set up their kids, however. Many societies still have "marriage markets," like South Korea, for example, where parents of single children who want them married go to try and find someone they believe to be suitable for their children. But unlike in the past, the children can still veto these arrangements and choose someone else or not to marry at all.

As trades that have to be passed down through family lines or through long, intensive apprintiships die out, fewer arranged marriages take place. The other factor is public elder care has increased, so children can pay to have their parents cared for in a facility, or by private workers. This has also lessened the need for a quick, assured marriage. As the culture shifts towards looking at the individual as a stand alone piece, instead of a cog in the family unit, arranged marriages will dwindle until they are a thing of the past, just as they have in European nations.