Air carrier flight crew reported conflicting ATC instructions during descent to VVNB airport.

Narrative

On descent into VVNB on Hakao1L. Was given several shortcuts on arrival. Last given was direct to SUDON descent to 7000. We were at 220 kts. Shortly before SUDON given descend to 4000 and cleared for the ILS Z 11L. Immediately after that given descend to 2000. Shortly after we were given maintain 4000 till DALAI. We were slowing to 200 kts. and in FLCH. 2000 in FCP ALT WINDOW from previous clearance. We were in the turn at DALIA to NB 360 when were told maintain 4000 due to terrain. Went ALT HOLD put 4000 in window and went vert speed 1000. When told to go to 4000 we were at approximately 3700 and again past DALIA. We queried ATC to confirm. They asked if we were VMC and we said yes. We asked if we were cleared to 2000 and they issued clearance to 2000. Uneventful approach and landing. No follow up from ATC. Compressed events during high workload phase of flight. Poorly issued ATC instruction that changed shortly there after. I was in FLCH. While very aware of restraints and terrain; VNAV however was more appropriate. VERY average ATC and poor quickly issued clearances and changes during high work load. We were aware of terrain in local area. Had briefed and hardened many altitudes on arrival to have more accurate VNAV. Several last minute shortcuts required FLCH to expedite getting aircraft back on profile. I had planned on going back to VNAV for constraint protects. It didn't happen due to the many quick events in the short period of time. VNAV would ensure compliance. We didn't to the best of our recollection miss those constraints or bust an altitude. Also the short period of time with clearances and instructions; the worst of which was descend to 2000; and then later maintain 4000 till DALIA led to concerns by ATC we might descend too low. We crossed DALIA at approximately 4000 and we're turning and descending to 2000 when we received the maintain 4000 for terrain. Other thing I would have done different if put 4000 in window when we received the maintain 4000 till DALIA. Compressed time for many clearances during descent phase and instructions that could have been issued better.