Abroad, a thousand separately enter coast, a part of peninsula (5,5)

I believe the answer is:

south korea

'part of peninsula' is the definition.
(part of the Korean Peninsula)

I cannot understand how the rest of the clue works.

(Another definition for south korea that I've seen is " Country with capital Seoul".)

I've seen this clue in The Guardian.

Want a hint initially instead of a full solution? Install my app