I came across this term in reference to a garden (Mehtab Bagh) situated across the way from the Taj Mahal….with no idea what it meant, I investigated.
I found a great website about Indian architecture that had this to say:

CHALUKYA STYLE
Fergusson, who chronicled Indian architecture, called the temple architectural style of the Middle Ages, the Chalukyan style, after the dynasty that ruled during that period. This name is not used anymore. n Char bagh gThe square garden. Char Bagh, an Islamic design, is a large square garden dvided into four smaller quadrants and water channels.

You can see the four quadrants in the plan for a Char Bagh style roof garden at the Ismaili Center in South Kensington, London.

“In Islamic style of architecture, the garden is not just another feature but has a well-defined meaning and it symbolizes the spirituality. According to the Holy Koran, a garden is symbolic of paradise. In Islam, it is believed that there are four rivers in paradise, one of water, other of milk, the third of wine, and fourth of honey. From this concept the Charbagh style of garden planning took root”.

The Ksar Char-Bagh Hotel beautifully used this design concept for the grounds of the hotel in Marrakech, Morocco.

SpaWorld has this description:

“There is water all around Ksar Char-Bagh a moat at the entrance, irrigation canals running around the gardens and grounds, the fountains, flowing over pebbles next to the stairs to the suites for Char-Bagh is the place in the Garden of Paradise where all the rivers meet.”

Add it to the list of places to go….