Unfortunately, many of our Bohary[Northern Egyptian] friends are quite ignorant of Sa3eedi people and of al Sa3eed in general. Many also don't study Egyptian history after the fall of the pharaohs,and often forget that many regions across Egypt have been settled by various non-Egyptian groups during even very recent times during the Medieval period.
First, you can often tell the origins of people from either their sur-name or family name. Most fellahin don't have these labels,but some Sa3eedis that live in Middle Egypt do indicating often either a Bedouin[Arab] or even a Berber origin.
Second, there are place names of certain villages named after certain off-shoots of bedouin tribes. Of course these bedouin tribes are not homogenous and have been settled and often became lost in the Fellahin population themselves. Either way often village names will tell the origins of the population.
Third, the local police and deputy for each governate throughout Egypt was not selected from the Fellahin population. Most times it was selected from either the ashraf or bedouin Arab populations. Ashraf are people who have papers sealed by the Egyptian government of their offical origins.
Fifth, during the Medieval era[640 AD-1500 AD] foreign bedouin Arabs were often settled in mainly the eastern Delta. Some were also settled in Middle Egypt. Around the 1300's Mamelukes settled Hawwara tribes[from Lower Egypt] into the area of Girga and Sohag. Most still maintained a nomadic lifestyle.
Sixth, the nomadic Bedouins brought to Egypt were eventually settled on land assimilating with the local fellahin population. Mostly in the Delta and Middle Egypt. These groups became sedentary cultivators.
Seventh, the nomadic Bedouins in the Western Deser and Oasis areas have lots of Berber admixture. Many are not really %100 percent Arabic anymore.
You ask where exactly did I get my information from about these bedouin Arabic tribes? Well, I actually obtain them from contemporary historians and writers that live in Egypt. Such as:
al-MaqriziIbn Khaldunal-Kindi