This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
The exact historical development of 厯 is uncertain. It appears to be a variant or older form related to 歴, but the component relationship is not clearly established.
The shape combines a cliff 厂 with 心 and 木 below, but no clear meaning emerges from these parts. Think of it as a mysterious old character whose meaning is lost.
For レキ, imagine a relic (レキ) hidden under a cliff: relic -> レキ, and the ancient relic's meaning is uncertain.