Elves society was stratified from the very beginning. Together with the original disciples and Uastra herself the Caste system was designed and changed little over time. Two large changes where introduced over time, parallel to numerous smaller adjustments.
The two large changes where the addition of the military caste, in response to aggressions with other races, and the adjustments that where made when the elf society merged with the fae society. The later change being very recent.
The old elf kingdom ( Alzahir kingdom) was recently fused with the old fae kingdom ( Sindhé kingdom) into the new Asgard kingdom as a response to the Utgard alliance, the merger has been a messy one with the elves seeing the outwardly expressive and emotional unstable fae as invasive to their tranquil culture.