This seems to happen fairly often when flying turboprops. I'm on course to an airport, descending into the approach space (e.g., "descend and maintain 9000"). Prior to entering the approach space and maybe 1000-2000 above the assigned altitude I get the instruction to "fly heading xxx, reaching 9000 resume own navigation", where heading xxx is usually perpendicular to the course to the airport. So basically you turn 90 degrees left or right, descend a bit more, then turn 90 degrees back toward the airport. Around about this time I am handed off to approach. If I had to guess, I'd say the intent is I'm being turned to keep me out of the approach controller's space until I can be cleared into it.Mark Kuebeler

you missed your crossing restriction of 9000 @ 40 miles from the arrival airport. the controllers is vectoring you perpendicular to your route of flight, until you are at 9000. at 9000 you should head back to the arrival airport.also because you are 9000 < 40 miles from the arrival airport, you're told to contact approach. make the crossing restriction, and you won't have this problemjd