Thabit ibn Qays was a Sahaba, a first generation Muslim, someone who was converted by Muhammad himself.
He played a prominent role in the meeting at the Saqifah.[1]
The largest tribe in Afghanistan, the Pashtuns, trace their lineage directly to Qays, who they consider to be the closest companion of Mohammed during his lifetime. It was the southern Pashtuns who formed the modern state of Afghanistan at the time when the Persian Safavid dynasty in the west, the Moguls in India and the UzbekJanid dynasty were all in a period of decline in the eighteenth century. The Duranni clan in Afghanistan claim descent from Qays' eldest son Sarbanar, while the other main Pashtun sect the Ghilzais claim descent from his second son. Qays' third son is said to be the ancestor of other diverse tribes, including the Safis around Peshawar .