yah kalah sata-sankhyayoh
tam evahur yugam taj-jna
yatra dharmo vidhiyate
sandhya--transitional period before; sandhya-amsayoh--and transitional period after; antah--within; yah--that which; kalah--duration of time; sata-sankhyayoh--hundreds of years; tam eva--that period; ahuh--they call; yugam--millennium; tat-jnah--the expert astronomers; yatra--wherein; dharmah--religion; vidhiyate--is performed.
The transitional periods before and after every millennium, which are a few hundred years as aforementioned, are known as yuga-sandhyas, or the conjunctions of two millenniums, according to the expert astronomers. In those periods all kinds of religious activities are performed.