the cotton textile industry is concentrated in Maharashtra and Gujarat because :
1. the availability of the raw materials i.e. cotton might be more.
2. the trade can be done easily because the Gujarat and Maharashtra have a lot's of sea ports where the trade can take place easily.
3. the availability of the industries and the factories may be more. hence making of the finished product from the raw materials can be done easily in the Maharashtra and even Gujarat.
hope so my answer is useful and mark as best if possible :D
Availability of raw material market facility moist and humid climate cheap labour well transport facilities