I've never done yoga before and don't know much about it. How about you?
I have not done it, but I would love to try. I know it is great meditative and spiritual physical exercise. 
Yoga
Hatha and Raja are the most common types of yoga.
Yes, I have heard it can be very relaxing. I wish I had more time to try it out. I could use doing something relaxing.
The origins are thought to date back to pre-Vedic Indian traditions.
I have never heard of those. Do you know more about them?
I am not sure other than yoga was mentioned in the Rigveda and was likely developed around the 5th and 6th centuries.