Hard work, you guys have no idea.
Try the 737-200 into PRC in the 80's. No FMS, magenta lines, map displays, GPS, RNAV approaches, TCAS, ACARS, fuel predictions, nearest airports, only two destinations with ILS but no approach lights, all other destinations with NDB only approaches to 400'agl, needed homemade timing device to configure before reaching minima, no VASI or approach lights, no piano keys or 1000" markings only an unlit "landing T", whatever that meant. ATC virtually non existent, constant frequency jammed in Mandarin or Cantonese, sometimes they just wouldn't answer at all, near misses, had a few we saw but who knows in that lousy weather. No roaming if we needed to contact the company, had to be a phone patch through HF, took forever. Best part was inbound seeing the lights on the border with HKG, could see them from 100 miles out on a good night, only viable alternate was goo-gan-zoo and they would only accept 3 or 4 diverting aircraft.
By the mid 90's we had all the good stuff and a multitude of new airports replacing the old Nanjing, Hangzhou, Chengdu, Pudong, later Goo-gan-zoo and numerous upgraded ones like Kunming and Xiamen. An absolute piece of cake by comparison although still unique and ATC remained a problem.
Out of interest I also did a check and typically 160 sectors in and out of the PRC was typical in around 1990 and how we looked forward to a Japan, Thailand or Nepal trip. In those days management guys did their fair share and didn't pick the eyes out of the roster.