Why is Guiness so prolific in South-East Asia? One thing I have noticed around South-East Asia is that the primary affordable dark beer is Guiness.  This appears to be due to high beer tariffs and the fact that Guiness has breweries all over (for example in Kuala Lumpur, Jakarta, and more places).

How did this come to be?  How did Guiness come to expand so far and wide?  Was it during colonial days or later?
Guinness licenses their brand and recipe to many breweries which is why they are so prolific everywhere. An example is the fact that Labatt's brews most Guinness sold in North America. So, their widespread popularity is simply a combination of marketing and smart distribution.