i don't know about 1400 years, I would presume that levels of co-existence varied from time to time and place to place. Not to mention that people can co-exist on a personal level despite oppressive state policies or can refuse to co-exist despite state policy that tries to create peaceful co-existence.
We know that there have been Jewish people living in the same spaces as Muslim people for centuries, and still do. Two obvious examples of this that have been true until very recently (and are arguably still true) is the significant population of Yemeni and Persian Jews in Yemen and Iran respectively. Maimonides talks about them in his Iggeret Teman. Admittedly the current population of Yemeni Jews is estimated to be less than 1000. In Persia (or Iran) the Jewish population has also decreased sharply but the roughly 25,000 inhabitants make them the biggest Non-israeli Jewish community in the middle east, also Khomeini issued a fatwa back in the 80's i think in which he guarantees the rights of Iranian Jewish within the Islamic republic. As far as i know the jews and muslims in Iran live in peaceful co-existence.
We also know that there have been Jewish Philosophers and theologians who have been deeply embedded into Muslim culture, an excellent example of this is Maimonides, sorry for the wiki-link.
Finally, the millet system in Ottoman Law is a form un-integrated peaceful co-existence.
Sorry, i know my sources could be better but I lost my access to Jstor etc almost a year ago
Sorry, I know my sources could
Muslims allowed other religions, but there was non-muslim tax. That's the biggest issue I know of concerning your question. This served more to convert than cause unrest though. Muslim rule was pretty cool with all the prophetic religions (christianity and judaism).
Please correct me if I'm wrong but I'm pretty sure Islam was pretty prosperous and worry-free until this century.
edit last century
It depends on where (geographically) you are talking about. There have been some places and eras where they have peacefully, and almost equally, co-existed (but this is rare). Mostly, there have been places where, under Muslim rule, Jews were allowed to live but they were discriminated against in much the same way they were in Christian nations.