朝鮮 ちょうせん通信 つうしん使 であれば
chōsentsūshinshideareba

Noun
Da Copula

The "-eba" conditional form ("if/when…") of 朝鮮通信使

1. If/When a Joseon communication envoy…; If/When the Joseon communication envoy were…

Ba Conditional