Pythagoras
It's in the ninth century BC.
10 BC was in the first century BC.
6th century BC.
The first century BC. Incidentally, there was no 0th century - BC or AD.
The year 560BC, as with any year between 600BC and 501BC, fell in the sixth century BC.
The sixth century BC:1BC - 100BC = 1st century BC;101BC - 200BC = 2nd century BC;201BC - 300BC = 3rd century BC...and so on:501BC - 600BC = 6th century BC.Remember that there was no 0 A.D., so the first century BC ended with 1BC, swiftly followed by the first century AD that started with 1AD.
a consititution
Alexander the Great overtook the Greek city-states during the sixth century BC. His rule was considered tyrannical control and is titled Hellenistic rule.
Scylax of Caryanda was a Greek navigator in the late sixth century BCE who explored the coast of the Indian Ocean for the Persian Empire.
in sixth century bc Islam appeared, which became serious rival of Hinduism. Even currently Islam is the biggest rival of Hinduism.
100 years.
In the sixth century BC the Romans adopted the hoplite formation of the Greeks. In the 4th century BC they abandoned it and replaced with the manipular formation of the Samnites. In 107 BC they abandoned this as well and developed their own formation.
Buddhism, but I wouldn't say that they are rivals, but complements.
Pythagoras
The year 340 BC is classified as the 4th century BC.
The 6th century BC began on the year 600 BC and finished on 501 BC. So from 2000 AD it is 2,500-2,600 years old.