New Social Group:
The new social group that emerged in the post-Gupta period was the offshoot of the large scale transfer of land revenue. It is known that during the post-Gupta period land-grants became universal.
Previously land-grants were made only Brahmins or religious establishments. But in the post-Gupta perk vassals and officials too were granted villages and land-revenue.
The recipients (grantees) of the land-grants were not a homogeneous group. That is to say, they all did not belong to any particular cast but by obtaining land-grants the recipients attained a social status that was much higher than the caste to which they belonged.
Why did not fit in:
The new social group that emerged did not fit in with the four-fold varna divided society.
The new social group that emerged as a result of the system of land-grants attained a social status that was higher than the varna to which he belonged by birth Thus the prevalent varna system became meaningless.
This evident from the fact that the new social group came to be known not by their varna, but by their new feudal titles such as thakur ranak and many such others.
The practice of land-grants also saw the emergence of a community of scribes, known as kayasthas. The community emerged from the need to prepare the documents of Ian transfer.
There is no evidence of such group in the varna divided society. Again there was the need to accommodate various foreign elements like the Hunas, Gurjaras and others in the society.
Yet there was no existence of such elements in the society. The foreign elements had to be accommodated in the existing society by breaking up the varnas into many castes (or jatis).