Excluding counting on the fingers, counting boards are the earliest known counting device, and a precursor of the abacus.
Dust boards were used as counting tools: Dust boards, which were essentially tablets covered with a thin layer of dust or sand, served a similar purpose to a counting board or a rough surface where calculations could be performed by making and erasing marks, according to kartsci.org. This allowed for the dynamic manipulation of numbers, which was necessary with the Indian numerals and their algorithms that involved moving and erasing numbers during calculations.
The earliest surviving example of a counting board or a gaming board may be a tablet found in 1846 CE on the Greek island of Salamis which dates back to about 300 BCE. Known as the Salamis Tablet, it is preserved in the National Archaelogical Museum, Athens.