Hangul is a very new alphabet. The Koreans didn’t have their own script until something like a century ago. Swahili has its own alphabet too.
A bit less recent than that. More like the 15th century for Hangul.
Swahili uses either modified Latin or modified Arabic for writing. Are you perhaps thinking of one of the invented scripts for indigenous American languages, e.g., Cree syllabics or Inuktitut?