foreign contingent; foreign participants; foreign competitors
Refers to a group of foreign people or entities in a competitive or comparative context, such as sports, business, or events. Often used in news reports.
The number of foreign participants in this tournament is the highest ever.
Domestic companies are exposed to competition from foreign players.
The suffix 勢 (ぜい) indicates a group or force, so 外国勢 emphasizes the collective presence or influence of foreign participants.
Compound of 外国 (がいこく, 'foreign country') and 勢 (ぜい, 'force, group'). The suffix 勢 is commonly used to denote a group or contingent, as in 若手勢 (わかてぜい, 'young group') or 地元勢 (じもとぜい, 'local contingent').