Looking at the first-ever records of Venus, the Babylonians have proof of the planet being observed around 1581 BC. The Persians also have a record of the transit of Venus in 1032.
It is easy to see Venus with the naked eye. Next to the moon, it is the brightest object in the night sky. People in the old days referred to Venus as the "morning star" when seeing it in the morning and called it the "evening star" when seeing it at night. They did not know that the celestial object they were viewing was actually the planet Venus.