Why does Egyptian art feature Nubian hieroglyphics

Egyptian art features Nubian heiroglyphics (“medu netcher”) because the culture of what is now called Egypt has its origins further south in Nubia. The culture of Nile valley civilization, particularly the belief and writing systems began in the south closer to the source of the Nile and traveled north. The culture flowed up the Nile just as the river does.The name Egypt came from the Greek name Aegyptos (which is the name that the Greeks referred to the land). The people of ancient “Egypt” called the land Kemet which is spelled “kmt” in the transliteration from medu netcher which means (“the black land”). The ancient “Egyptians” also referred to the land as twi (transliteral spelling may be off) but is prononounced “tau wee” which means 2 lands. This refers to the unification of the northern and southern kingdoms.There were also Nubian pharaohs at times and the Nubians even ruled Egypt at times. There have been discoveries of older versions of medu netcher (“heiroglyphics”) in Nubia that pre-date the dawn of the dynastic periods of ancient “Egypt”.