The term 'Yoga' means union or association of two things. In Vedic Astrology 'Yoga' refers to association of planets, which yields specific results. The association of planets may primarily occur through (i) conjunction, (ii) mutual location in each other's sign, and (iii) by mutual aspect.
Among the 12 houses of the horoscope the 3rd, 6th, 8th and 12th house are regarded Triksthana (inauspicious). Among these the 6th, 8th and 12th houses are regarded Dushsthana (evil). The rest of the houses (i.e., 1st, 2nd, 4th, 5th, 7th 9th, 10th and 11th are regarded as good houses. Among these also kendras (1, 4, 7, 10) are called Vishnusthana (sonferring happiness), and (1, 5, 9) are termed as Lakshmisthana (Conferring wealth. Thus Kendras and Trikonas are regarded as the most benefic houses.
The astrological classics describe the 'Yoga' (combination) of strong lords of benefic houses as Raja Yoga or Dhana Yoga, and mention the benefic results produced by these. The Yoga formed by the lords of malefic houses are called Duryoga (malefic) or Arishta Yoga (destructive).
For some Lagnas, a single planet becomes lord of both a Trikona and Kendra. For example, for Taurus Lagna, Saturn is lord of 9th and 10th house; for Leo Taurus Lagna, Saturn is lord of 9th and 10th house; for Leo Lagna, mars is the lord of 4th and 9th house; for Libra Lagna Saturn is the lord of 4th and 5th house; and for Aquarius Lagna, Venus is the lord of 4th and 9th house. Such a planet is called Yogakarka for the horoscope and produces very good result. When a yogakarka associates with other benefic planets, then better results are experienced by the native.
According to Laghu Parasari
meaning, "If the powerful lord of a Kendra is associated with a Trikona lord, it produces Raja yoga and gives auspicious results to the native."
The 10th house is the most powerful kendra, and the 9th house is the strongest Trikona. These houses relate to the most important aspects of life. The 9th house relates to Dharma (religion), Bhagya (Luck), etc. while the 10th house relates to Karma (profession), status, honour, etc. According to Phaladeepika (6.37) :
meaning, "When in a horoscope the lords of the 9th and the 10th house together occupy an auspicious house, it constitutes a Raja Yogaa. When the lords of other Kendra and Trikona houses are similarly placed, i.e., join together in an auspicious house, the resulting Yoga is called 'Sankha'. The Raj Yoga formed by the 9th (dharma) and 10th (Karma) lords is famous as Dharma-Karmadhipati Raja Yoga (DKRY).The native with strong DKRY in his horoscope attains high status, success and fame in his profession. The native born with Sankha Yoga is blessed with all types of comforts in life.
Uttarakalamrita further elucidates :
meaning, "The Raja Yoga formed by the following planetary combinations in a horoscope confers wealth and happiness to the native :
The lords of the 9th and 10th house are in their own house.
These lords are together in the 9th or 10th house.
These exchange houses or Nakshatra.
These aspect each other.
These are with the lords of 1, 4, 5, 7 house.
These are in 1, 4, 5, 7 house.
But these two lords should not own the 8th or 11th house." It further adds.
that is, "the three pairs of planets :
The owners of the 9th and 10th houses from Lagna
The owners of the 9th and the 10th from the 9th house, and
Lords of the 9th and 10th house from the 10th house respectively give high, medium and small position to the native."
To produce the best result, the Yoga should be formed in a benefic house. Further, according to the ownership of planets for different Lagnas:
The Raja Yoga gives best result for Virgo and Pisces Lagna, as the 9th lord is a benefic for the Lagna and the 10th lord is also the Lagna lord.
It produces very good result for Taurus, Cancer, Sagittarius and Capricorn Lagna.
In Aries, Gemini, Leo, Libra, Scorpio and Aquarius Lagna, the 9th, 10th and Lagna lord are not friendly to one another. Hence, only mixed results are experienced by the natives.
In modern scenario, a native with strong DKRY in his horoscope may become a prosperous businessman, successful politician, scientist, Cinema Star, etc., and achieve great success and fame in his field of activity.
The horoscopes of some famous personalities having DRKY are discussed below.
Shri Rattan Tata, Leading Industrialist.
The combination of lords 9th (sun), 10 (Mercury) and 11th (Venus) in Lagna, aspected by 2nd lord Saturn has made him a successful and famous industrialist.
There is exchange of lords of 2nd and 4th house, and Gajakesari Yoga formed by Jupiter in 2nd and Moon in 11th house. Lagna Lord Jupiter and 5th Lord Mars aspect 10th house.
Shri Arjun Singh, former Governor, and Central Minister.
The 9th lord Saturn is in 7th house, and the 10th lord Jupiter is in Lagna. Both aspect each other. The 10th lord Jupiter aspects 9th house and 9th lord.
from Moon Rasi also the 9th lord Jupiter and 10th lord Saturn aspect each other.
The Yoga result has given him political success. As from Lagna the 9th lord Saturn is also lord of 8th, he had to face many ups and downs in his political career.
Shri Anil Kapoor, Film Actor
Yogakarka and 9th lord Venus is in 9th house itself. 10th lord Mars is in 10th house, with 2nd 11th lord Jupiter and 5th lord Mercury. This planetary position has made him a successful, wealthy and famous Cinema Actor of Bollywood.
Shri Amitabh Bachchan, Film Star.
9th lord Venus and 10th lord Mars are conjoined in the 8th house. Venus gets Neechabhanga being with exalted Mercury. He has enjoyed great success in life. There is Gajkesari Yoga . The aspect of 5th lord Mercury, 9th lord Venus and 2nd and 11th lord Jupiter on 2nd house (face and speech) has been instrumental in his success in films. As the DKRY occurred in 8th house, he also had to face serious physical and financial set-backs in life.
Murli Manohar Joshi, ex-President BJP and Minister
The Buddha-Aditya Yoga in 11 the house aspecting 5th house has made the native a scholar.
The 9th lord and Yogakarka Venus and exalted 10th lord Mars conjoin in 12th house, with Lagna lord Saturn and Rahu. The combination is aspected by Jupiter located in 8th house, and also by Ketu from 6th house.
The conjunction of powerful 9th and 10 th lord in 12th house did confer high status and fame to him after great struggle, and he had to face secret opposition from own party colleagues against further rise.