I know they are Indian. I am from South Asia. However, the modern system was first created in Arabic. Also, I am talking about the placement of the digits, and this came to Europe from Arabic, not Brahmi.
Arabic has a large variety of sounds - but I think no more than other languages do. For example, Arabic does not have a p sound or a g sound. My native language, though, has 4 types of t and 4 types of d, 2 types of k, 2 types of g, etc.
Have you ever wondered why numbers are written backwards in English? Why do we write the highest-order digits first and proceed to the lower-order digits?
Well these numbers originated in Arabic, and since Arabic is written right-to-left, writing numbers in Arabic actually follows a more logical order: start with the lowest-order digit, and move on to the higher-order ones.
Apparently when the concept was brought into Europe, they failed to account for the different writing directions.