Some globes may have publishing dates on them. That said, my Cold War-era map does not. What it does have is the name of the cartographer and which series it is a part of. I would imagine that is the best way to research the publishing date.

That said, it's a globe from the US where that sort of thing is required. I dont know if Korea has any such requirement.

Using the nations you've mentioned, here is some other information:

• Indo-China broke apart over a series of years (1953-54), beginning with Laos (22 Oct 53), followed by Cambodia (9 Nov 53) and ending with Vietnam (which is its whole other thing that I'm not getting into right now).
• Belgian Congo became independent in the '60s, so that isn't any help here.
• The Korean War started in 1950, but if you found that globe in Korea it's entirely possible they were hoping it wouldn't be a divided Korea, so while it was probably made before 1953 (based on this fact), there's no way to be certain.

I would advise looking up "decolonization in [continent]" (where [continent] is replaced by the continent in question - Asia, Europe, whatever) on Wikipedia. It's not exactly Decline and Fall of the Roman Empire, but it's good enough for your purposes.

You missed one of the bigger age determinators for 20th century maps: the presence of East/West Germany (post-WWII vs. pre).

Your map is either one printed immediately post-WWII or likely an early 20th century map, you'd need to provide more details to determine which. Prior to 1945 Korea was occupied by the Japanese, though some maps printed it as a region with the same color as Japan (to indicate the occupation) while some printed it as a different color. And prior to 1910 the "Empire of Korea" existed, which some map makers would just have printed as "Korea".

So, to go through the list:

• United Korea: pre-1948 (the division of Korea into North and South protectorates occupied by the USSR and the US et al), post-1897 the transition of the Choson dynasty to the Empire of Korea, post-1910 Japanese occupation of Korea
• Indo-China: at least pre-1948 (when French Indo-China got split up into different bits)
• Belgian Congo: pre-1960 (independence), post-1908 (previously the, euphemistically named, Congo Free State)
• Czechoslovakia: pre-1993, post-1918 (when it was created out of the remnants of Austria-Hungary)

Given that, the map is either from the interwar period or from the immediate post-WWII period. The presence of East/West Germany and other post-WWII changes will be the big give away.

As for dating maps based on the contents, wikipedia actually has a pretty decent list (as loathe as I am to link wikipedia): https://en.wikipedia.org/wiki/Timeline_of_historical_geopolitical_changes

However, be aware that nothing is ever so simple. Map making is inherently a lot more subjective and political than most people believe. There are always choices when making maps (see above on the choice of coloring Korea the same or different relative to Japan). Additionally, sometimes events outpace map makers, and maps are made that are outdated even when published. Geography is dynamic, and sometimes it's not obvious how serious a "geographic error" is during the moment of transition, let alone what the "correct" labels and borders are at any given moment of time from the perspective of the near future. This is a big reason why you don't see a lot of maps and globes published during wars where a lot of change is happening fast. Maps are always a way of trying to predict the future, because that is the period where they will be used, although things have changed slightly in the internet era.