I don't believe I've listened to any kpop song older than "Kiss - Because I'm a Girl", but I do know many singers that started in the 90s who had songs in the 2000s :

Shinhwa -  Without You, Gonna be Alright

Lee Seung Chul - Fate, No One Else, Malri Flower

Fly to the Sky (?) - Missing You, My Angel, Question


I find that most ppl don't listen to anything before Big Bang's Haru Haru (2008), so even those feel really old already.

 Jay:

I don't believe I've listened to any kpop song older than "Kiss - Because I'm a Girl", but I do know many singers that started in the 90s who had songs in the 2000s :

Shinhwa -  Without You, Gonna be Alright

Lee Seung Chul - Fate, No One Else, Malri Flower

Fly to the Sky (?) - Missing You, My Angel, Question


I find that most ppl don't listen to anything before Big Bang's Haru Haru (2008), so even those feel really old already.

I dont listen to any 3rd gen idols  such as exo and bts 

well this is probs my 2nd fave song by him after fate:  boohwal -  never ending story  (vocalist: lee seung chul)


but anyways theres a ton of amazing 90s singers such as:

Kim Min Jong  (my fave actor and 2nd fave singer)

Lee Jung Hyun

Uhm Jung Hwa

Lee Hyun Woo

COOL (mostly just Lee Jae Hoon cuz hes just awesome)

Sechskies (even the rappers can sing well, especially eun ji won)

g.o.d

YB (Yoon Do Hyun)

yurisangja 

roor'ra

Vibe (Yoon Min Soo debuted in the 90s with 4men) 


early 2000's:

Sung Si Kyung (my fave singer, i listen to his songs whenever i can ) 

SECHSKIES

I got to know them after their reunion. Their songs are awesome! ♪♪..shake that booty!!♪♪

I would love in an appreciation for an K-Pop label agency to upload 90s songs on Youtube, i know how many other users upload 90s K-pop without permission from the Label agency.

(sorry for my poor English)