Slavery tolerated because of "necessity" means that you do not really want to do it, but you think you must do it. An example is when you have a farm and you need people to work on it. The trouble behind this scenario is that your farm isn’t making money to pay your farm helpers their proper wages, so you resort to slavery. In this case, you do not need money for salaries because your farm is doing well to keep your slaves clothed and fed.
Slavery affirmed as a "moral right" is when you think it is your right to be the master and the slaves deserves to be slaves.
What does all of this mean 555555555555555555
According to the mythology Ramayan happened first and then comes mahabharat.
There are some evidence that does suggest the happening of a great war about 3500 years ago which could be the origin of the epic of Mahabharat but no historical or archeological evidence is available for Ramayan.