When does Dhaiya occur?
According to astrological beliefs, Dhaiya occurs when Saturn or Shani moves over the fourth or the eighth house from the natal moon. The transit over the above mentioned houses have both positive and negative effects on the native..
Since the planet Saturn or Shani consumes 30 years to complete one round of a zodiac, the Dhaiya remains prevails for two and a half years. The unique thing about Dhaiya is that everyone has to go through it. Since the planet moves slower in comparison to other planets, the Dasha caused by the same prevails for a long time. This two and a half period of Shani Dasha in one's chart or Kundli is known as Dhaiya.
The effect of the planet Saturn or Shani and its baneful placement on the native's chart gives way to baneful or ill effects/events. It happens because the positive effects of the Moon are subsided due to Shani's overpowering nature.
Mythological beliefs suggest that during the time when Lord Shiva was delegating work and responsibilities to his disciples, the God of Saturn or Shani Devta was assigned the duty of punishing people who were evil. From then on, Shani Devta has been punishing people for their inhuman and immoral deeds.