However, there were a number of other councils held in Ceylon and Thailand between the fourth and sixth ...
What are these other councils? Where where they held? What was their significance?
What are these other councils? Where were they held? What was their significance?
I am going to try to answer this to the best of my abilities.
I do not know the specifics of where they were held, but I do know what they are & their significance.
All the Buddhist councils are meant to preserve the Dhamma the Buddha formulated & to discuss the Tipitaka & its interpretations.
Buddhist councils have not consisted of all schools unified, although in some cases they have been.
I hope my answer suits you well! :)
May you be well.
Here is a descriptions of some of the councils and their significance http://en.citizendium.org/wiki/Buddhist_councils