Part of the reason for Egypt's (Kemit's) decline was due to inevitablity. All civilations eventually decline after reaching a peak. After hundreds of millenniums of uninterupted existence, a series of internal problems and invasions by outside cultures (Persian, Hyksos, Greek, Roman) signaled the end. Egypt was not a monolithic culture. It was the fruit of Africa and had been ruled by various ethnic African cultures and peoples from Eastern, Western and South Central Africa. Egypt's wealth, advanced civilization and location made it a beacon for other cultures located in Asia, especially Western Asia (Europe) and the Mediterranean basin.
Note: This question was originally placed in the Science category and generated both science and religion based responses. Subsequently, the original poster reiterated his desire that the question be answered in a scientific rather than a religious context. Quote: I put it in here, because I want a scientific answer. Unquote
Considering the fact that this question was placed in the Science and Environment FAQs rather than in the Religion and Spirituality FAQs, an appropriate response would be that "hominoids," which belong to the Hominoidea super-family of primates and include apes and humans, are thought to have first walked on earth around 6 million years ago.
For those who are looking for an answer based on religious teachings, please see related questions in those categories.
In Macedonia and many places where he conquered between Macedonia and India
and he tried to conquere Africa also he conquered
The ancient egyptians had a monarchy. So thay had _3_ branches in ancient Rome.
The Phoenecians controlled the coastal areas of Lebanon and Syria from around 1200 to 300 BC. Their main home cities were Sidon and Tyre. They established colonies in Cyprus, Malta and Spain, and famously, Carthage in North Africa. Their empire declined after Tyre fell to Alexander the Great. Hope this is of help.