The main shrine in Mecca which houses the Siva emblem is known as the Kaaba. It is clothed in a black shroud. That custom also originates from the days when it was thought necessary to discourage its recapture by camouflaging it.
In India the crescent moon is always painted across the forehead of the Siva symbol. Since that symbol was associated with the Siva emblem in Kaaba it came to be grafted on the flag of Islam.
Another Hindu tradition associated with the Kaaba is that of the sacred stream Ganga (sacred waters of the Ganges river). According to the Hindu tradition Ganga is also inseparable from the Shiva emblem as the crescent moon. Wherever there is a Siva emblem Ganga must co-exist. True to that association a sacred fount exists near the Kaaba. Its water is held sacred because it has been traditionally regarded as Ganga since pre-Islamic times (Zam-Zam water).
Note Even today Muslim pilgrims who go to the Kaaba for Haj regard this Zam-Zam water with reverence and take some bottled water with them as sacred water
