A ceremonial hat from the Wrangell Kiks.ádi tribe was set to go before the auction gavel in New York Wednesday.

The potential auction of a priceless heirloom has galvanized tribal leaders, who say the hat never should have been sold in the first place. A rally with traditional singing and dancing was planned for Wednesday evening in Juneau. A crowdsourcing campaign to try and reclaim the hat had raised more than $21,000 in three days.

The auction, being conducted by the New York chapter of international art auctioneers Sotheby's, illustrates a clash between concepts of ownership, and harke...