IPA: /ˈeɪnʃəntli/
KK: /ˈeɪnʃəntli/
In a way that relates to a very long time ago or to ancient times.
The ruins were anciently significant to the civilization that built them.
Anciently → It is formed from "ancient" (from Latin *antiquus*, meaning old or former) and the suffix "-ly" (meaning in a manner of). The word "anciently" refers to something that is done in a manner relating to ancient times or in the way of the ancients.
Think of 'ancient' meaning very old, and '-ly' indicating a manner. So, anciently means in the manner of ancient times.