[1] Shatsthala is a conflation of Shat and Sthala which means 'six phases/states/levels' through which a person (a bhakta/seeker) advances in one's ultimate quest of realisation of the Supreme, or, simply put, enlightenment.
The Aikya Sthala is the culmination where the soul leaves the physical body and merges with the Supreme.
[3][4][5] While the origins of the Shatsthala may be traced to the Agamas, particularly the Parameshwaratantra, with the evolution of Lingayatism the evolution of concept of Shatsthala was also unavoidable.
While Basava understood Shatsthala as a process with various stages to be attained in succession, the credit of refuting this and redefining Shatsthala goes to Channabasavanna, Basava's nephew.
Channabasavanna differed radically from his uncle and held that a soul can reach its salvation in any stage.