There are many Sufi groups and their practices differ from one another. As far as I know, all the Sufi groups practice zikr (sometimes spelled as dhikr) individually and collectively. The word "zikr" is literally translated as "remembrance" (of Allah). This practice consists of repetition of some word (one of the names of Allah, for example, "Ya Allah" - "O Allah") or some phrase (for example, "La ilaha illa-Llah" - "There is no God besides Allah").
There are different ways of how different groups practice zikr. For example, some Sufi groups practice collective zikr with dances while other groups practice zikr only sitting. Some Sufi sheikhs even accuse other Sufi groups of practicing zikr in the wrong way.
The following videos were made in Chechnya and they show how collective zikr is practiced by Chechen followers of Kunta-hajji Kishiev (Chechen Sufi sheikh who lived in 19th century and belonged to Qadiri tariqah). I do not promote this practice. On the other hand, I am not going to make any conclusions here whether this practice is mind-controlling, thought-stopping, meditative, and so on. I post these videos only for the information on how this practice is performed by some Sufi groups.