Shifatur
I think there's a few points to mention
1/ You need the right to legally work where ever. Citizenship/permanent residence or a work permit etc.
2/ A licence that permits you to fly a/c registered in the state you are wanting to work.
The above may seem obvious but it's fact ( i.e. in the EU it's a JAR licence and an EU passport)
You say that you are going to be getting a South African fATPL, which isn't a bad licence to have depending on your personal circumstances.
You can't obviously fly in the EU with the SA licence. Nothing wrong with the standard of training (all ICAO standards etc), you just need to spend in excess of £30K to have the appropriate bits and pieces to be legally allowed to be a flight crew member (I think from memory there was a good post on the African forum about the conversion about 6-9 months ago - not sure if its in the archives)
The SA licence also carries with it a lot of favour if you want to go and fly in other African countries. Granted this may not be everyone's cup of tea but it is a good way to build up the hours from three figures to four.
Although I'm not going to go into details, once an any ATPL is unfrozen (1500 hours+) generally more doors will open and it may then be possible to have licences validated in other countries around the world.
Of the airlines which usually employ foreign pilots I think the most well known are Emirates, Cathay, and Singapore. Granted these carriers usually look for 1000s of hour jet time but I know of many ex SA pilots now employed with these carriers.