wikipedia article) Ladies or maids will wash the court yard of the house early in the morning and put rangoli.
Two days back, it suddenly flashed to me. What is the reason behind rangoli? Well, every person will have a creative itch. The poor women, who rarely go out of the house do not find any outlet for this. By putting a beautiful rangoli, they will satisfy their need to express themselves. So is the case of devara nama (devotional songs sung during pujas )
Good, our ancestors thought at least something about the needs of women!!
Again that is my theory. If you ask some other people, they may say it is to welcome God and Guests to our houses.