You should really travel at least 1000miles, but so long as you reached Kazakhstan by driving at least 5000 miles to get there, or 1000miles whilst there, you shall qualify, to some degree. It's basically flexible, you do it all as you discover it. Ideally you might go by some key waypoints in Kazakhstan, like; Uralsk, Aktau, Aktobe, Aral Sea that isn't a sea, the sputnik space launch site, Shymkent, Almaty, Talas, Astana. Or if you like to say that you travelled up to China, you can go to the lovely atmosperic market town of Zharkent and then to the Khorgas KZ-CN border. There are all places I travelled to myself, I don't suggest you try to go sme place that I didn't see is nice and characterful with my own eyes and 2 feet, or wheels!