Mahatma Gandhi first established the Satyagraha Ashram in Ahmedabad in 1915.
After returning to India from South Africa, Gandhi founded the ashram at Kochrab, near Ahmedabad, on 25 May 1915. It was initially known as the Satyagraha Ashram and served as a community for residents committed to truth, non-violence, simplicity, and communal work.
The ashram later moved to the banks of the Sabarmati River in 1917. That second location became famous as Sabarmati Ashram and was the starting point for the 1930 Salt March to Dandi. The original Kochrab site remains historically important but is often overshadowed by the later Sabarmati location.
This question concerns the city, not the river or the later ashram site. Ahmedabad was also an important center of textile manufacturing and labor activism, including Gandhi’s work with mill workers in 1918.