Conversation so far:
Where does Celtic art come from?
Celtic art is associated with the peoples known as Celts.
What are the influences?
Archaeologists identified various cultural traits of these peoples, including styles of art, and traced the culture to the earlier Hallstatt culture.
What was the Hallstatt culture?
CANNOTANSWER.
What are popular pieces of Celtic Art?
CANNOTANSWER.
Are there any other interesting aspects about this article?
The term "Celt" was used in classical times as a synonym for the Gauls (Keltoi, Celtae).
What does the word mean?
The ancient peoples now called "Celts" spoke a group of languages that had a common origin in the Indo-European language known as Common Celtic or Proto-Celtic.

Question: What time period is this?
Self-contained rewrite: What time period was Celtic art made?