While early Islam does seem to have several significant safeguards for female rights, you also have stories of women like his wife Khadijah, who was a business owner and initially employed Muhammed. Did Islam make things better or worse for women in the region in the short-term?
I think you'll have to be a bit more region specific. Nejdi bedouins probably had different ways of treating women than Meccan traders and eastern Saudi was a part of Iran at the time.
I can't give a specific answer but I do have a book suggestion. It's called Women, Gender, and Islam by Leila Ahmed - she focuses mostly on Egypt but talks about women before Islam and the changes they experienced as a result and might be a good foundation for your understanding of how Islam changed (and adapted to) each region's indigenous culture. It also shows how Islam changed over the centuries to how it is today.
It's worth noting that there was no Saudi Arabia prior to the spread of Islam. There was the Arabia Peninsula, but the modern day Nation-State of Saudi Arabia is, quite literally, named for the first king/current ruling dynasty (and was called the Kingdoms of Nejd and Hejaz before being renamed), the House of Saud. The modern Nation States dates to the 1930s (although there were two previous Saudi States, those ceased to exist for some time under Ottoman rule).
It may seem like a minor nitpick, but it can be a very important distinction when talking about State level history and historical events, because States can attempt to use history as justification for modern actions.