"Eight ills" are in ancient Chinese poetry about poetry sound legal terms, often with the "four tones" and mentioning a Five Characters ancient one Metrical rules.

八病是中国古代诗歌中关于诗歌声律的术语，是经常与“四声”并提的一种五言古诗格律规则之一。

youdao

Nanyang folk song has a mode of five tone, which includes four, five, six and seven tones.

其中也包括有五声性的四声、五声、六声和七声调式。

youdao

It's a major-key sound, but unlike our major keys, which have a half step between the third and fourth tones, the Lydian scale has a whole step there, and the half step between steps four and five.

WSJ: Making Music Against the Odds | Ensembles of Afghanistan National Institute of Music