This sign shares a common root with the Chinese character qiǎn or kǎn 凵, which means a receptacle, or container.
It is often incorporated into the Indus motifs, where it represents the body of a cart or carriage.
There are many examples of this sign in the Indus texts.
Illustrative Text Reference:
Harappa: Seal: H-1710 A: Asko Parpola, B. M. Pande, and Petteri Koskikallio, 2010: Corpus of Indus Seals and Inscriptions: Volume 3,1: Page 238: New material, untraced objects, and collections outside India and Pakistan: Suomalainen Tiedeakatemia.
Comment:
The spoken Indus language is not within the scope of this dictionary. However, Stuart Piggott said that in the Rigveda, the word for the body of a chariot was the same as that used for a bucket (kośa)¹.
In my opinion, that corresponds to the evolution of the pictographs, whereby the bucket from the Grotte de Bayol becomes the cart of the Indus Valley Civilisation².
Image Credit:
Indus Script Sign Number 1206: List of Sign Variants: Iravatham Mahadevan, 1977: The Indus Script: Texts, Concordance and Tables: The Director General Archaeological Survey of India.
Notes:
1. Stuart Piggott, 1950: Prehistoric India to 1000 B.C., p.278: Penguin Books, Middlesex.
2. A drawing at the Grotte de Bayol, Collias incorporates the container symbol: The Cave Script Translation Project: Lynn Fawcett, 2013: http://www.cavescript.org/research/work/manual-labour/