The problem with very old historical stuff including the origins of a certain concepts and giving due credit where it is due is one of the most difficult questions in history. The truth is that we may never know the correct picture behind the question who invented the modern number system? No matter what Wikipedia says. Anyone who is serious scholar of scientific history, Wikipedia should be their last resort to provide a proof. It must have been a very slow progress based on cross-cultural exchange of knowledge. About a thousand years ago, Middle east and central Asia were the center of knowledge just like today's Europe and North America. Some scientific words from Arabic origin still linger in modern mathematics and chemistry, such as algebra (named after a treatise with this title), algorithm (named after an Arabic mathematician), alcohol, boron, chemistry, alkali, natron etc. This shows that translation of Arabic into Latin was an active process in Europe. Translation is a sign of a progressive society.
For instance, OED entry for Arabic numerals traces the word usage history:
Designating the system of numerals written 0, 1, 2, 3, 4, etc.; of or
relating to this system. Chiefly in Arabic numeral. Contrasted with
Roman. Arabic numerals reached western Europe through Arabia by c1200, but probably originated in India
The earliest usage goes back to 1750s:
1756 Gentleman's Mag. May 239/1 The learned are not quite agreed
when the Arabic numerals were first brought into use in this nation.
which clearly shows that nobody was even sure when these numbers were brought to Europe. Also note the word probably. Some falsely imply that these medieval Arab scholars were mere translators of Greek and Indian works. This is a fabricated story as well because as stated above, translation of scholarly work is a part and parcel of science.
Civilization near the Indus valley (now India, Pakistan) have 3000-4000 year old culture and they had their system of weights for trading. Certainly, they knew how to count as well. China had its own set of philosophers. Since the languages of these cultures was so different, it is extremely difficult to trace the ancient history of science. There is very little primary source of information. Today we can look up 18th century articles and say that this and that person is behind this concept but this does not apply to older works. If the Egyptians could build such huge pyramids thousands of years ago (predating all) which still startle modern civil engineers, can we say that they knew trigonometry very well? Nobody knows, because they did not leave anything which we can understand yet. Who knows how much knowledge was lost with time and then re-invented.
Recently, there are series of rather ridiculous claims in History of Science and Mathematics, and even Physics that everything originated in ancient India. Claims range from invention of alegbraic formulae, sine, cosine, numbers, astronomy, distance between Earth and Sun, ancient aircrafts, stem cell research and above all close relationship of German and Sanskrit. Usually Wikipedia and other dubious sources are quoted. BBC even made a report on it, sadly this is being propagated by some obscure university professors. One can only imagine how many students are misled. Perhaps these awed students are posting a series of these questions all over the web.
India: scientists dismiss Einstein theories
The moral of the story is that paper never refused ink. Web is worse, because everyone can propagate false ideas. Our job is to filter junk vs. good work.