Hello again! You will find quite a number of posts on this forum if you search for Patanjali, yoga sutra, or classical yoga. Raja yoga (royal yoga) is just another name for it. This yoga was written down by Patanjali somewhere before 200 CE. It is recognised as one of six official Hindu philosophies (darshana). It is a gem and contains the famous eightfold yoga of yama, niyama, asana, pranayama, concentration, meditation, absorption. I’m going to put this very delicately now: I don’t know whether Brahma Kumaris teaches this raja yoga or is using the name for teaching something completely different. Perhaps other forum members will comment.