Given the two options, I would go for the second...
However! What I would consider to be the best option is a third alternative. Something that combines information and instructions:
This format gives the user a hint of what to write and expect. It's easy to understand that
example.com/europe/ gives available countries in Europe and that
is the URL for viewing San Francisco.
Your options doesn't really tell the user what to expect. What region is 1? Which one is 2? Was it
/3/3/2/4/ for Paris?
I understand that using a text-ID for a city might not be feasible for you, but it's nonetheless the option I would recommend.
Some friendly reminders on the way:
Keep in mind that the use of regions are different depending on the
culture of the user. Americans might be used to enter information
about their state, while a Swede doesn't really put any significance
in the region and would prefer to write
Remember to be kind to users who makes mistakes and writes
/europe/cannada/toronto/ Don't just tell them "Incorrect country
ID" but help them remedy their mistake by saying something like
"Cannada is not a country in Europe" or simply fix the error for them.