The Maltese is an ancient breed, originating
8000 years ago. However, quite a bit of development occurred that lead to the white coat that we see today.
The Maltese was not always found with just a white coat. During a short period from 1902 to 1913, the KC (Kennel Club of the UK) allowed all colors in show. With Maltese other than white, the coat was said to be much coarser and not as silky as their solid white counterparts.
In 1877, a pure white Maltese was shown at the Westminster; at that time he was called the Maltese Lion Dog. Two years later in 1879, a white Maltese with black ears was shown at the Westminster, and was dubbed the Maltese Skye Terrier.
Once the Maltese piqued interest in some breeders in the United States, crossbreeding was done to perfect the breed. It is believed that the eventual goal was a dog that was smaller in size (those first shown at Westminster were 10+ pounds) and to bring the coat to white only.
One record that showed a crossbreeding was to a Pomeranian which produced black puppies. However, the most common pairings were to white toy Poodles; this took place from 1900 to 1910 across the U.S.
It is important to note that during this time there were very few Maltese registered with the AKC. There were just 6 in 1902, and then 50 in the 1950's.
From the 1950's on, the Maltese evolved into a solid white dog, though there can be a touch of color, which lingers from his rich history.