How did 이르다 get transformed to 이르러서는 in this sentence?

Question

i have a sentence as follows:

얼굴에 탈을 쓰고 추는 춤인 탈춤은 가면무용이라고도 한다. 신라시대에 유행한 처용무 등이 궁중무용으로 전해지더니, 이것이 고려· 조선 시대에 이르러서는 민속무용으로 크게 계승, 발전하 였다.

As I think in this passage, 이르러서는 = 이르다 + 아/어서 + 는. However, if that's the case, then from what I've learned about division 아/어서, 이르러서는 should be 일러서는, right? And what is the function of 는 here?

Answer 1

이르다 is a special or tricky one! It has many meanings. In this case, it means to “get to“, which is an adjective in Korean. It belongs to the 러 irregular verb/adj NOT the 르 irregular verb/adj.(as you thought: 일러서는). *러 irregular verbs/adjectives : 이르다, 노르다, 누르다, 푸르다

The function of 는 in that sentence is to show contrast! Comparing 신라시대 and 고려, 조선시대! 는’s various functions are here explained. https://youtu.be/3Ra3XS-L0VU

I hope it helps.

Answer 2

Kimexplainskorean gave a great answer. Just to add on to it, 이르다 is especially tricky because the conjugation actually differs depending on the used meaning, which is common in languages like English but (luckily!) very rare in Korean. In fact, 이르다 is the only commonly used one I can think of, maybe someone else here has more examples. When using 이르다 to mean "early", it is indeed conjugated "일러서" like you suggested.

Answer 3

When the liaison ㅓ/ㅏ is added to the predicate stem of 이르다, the conjugation is 이르러.

When the liaison ㅓ/ㅏ is added to the predicate stem of 이르다, the conjugation is 일러.

When the liaison ㅓ/ㅏ is added to the predicate stem of 이르다, the conjugation is 일러.

There are 3 different predicates, each having a separate entry in the dictionary, which are homonyms in their unconjugated form.

As for 는, recall that 은/는 and other particles like 이/가, 도, 만 can follow another particle, not just nouns.

Answer 4

1. 이르다 to arrive

이르러서는

마을에 이르러서는 우리는 헤어졌다.

2. 이르다 to tell on, to snitch

일러서는

절대 선생님께 일러서는 안 돼!

3. 이르다 to be early

일러서는

너무 일러서는 힘만 들 거야.