The history of tanis :

Tanis was a brand new city in ancient Egypt and served as a parallel religious center to Thebes in the Third Intermediate Period. No archaeological evidence from it pre-dates the reign of Psusennes I (1039-991 BC), but many scholars think it originated in the late New Kingdom. Tanis's creation was most likely due to the silting up of the Nile branch that ran by Pi-Ramesses, which forced people to seek another area with access to water. Later on, Tanis would become known as Thebes of Lower Egypt.
The kings at Tanis saw themselves as the legitimate successors on the throne of Upper and Lower Egypt. They used traditional titles and displayed their royalty in building work, although that was insignificant when compared to activity at the height of the New Kingdom.
Tanis was founded in the late Twentieth Dynasty, and became the northern capital of Egypt during the following Twenty-first Dynasty. It was the home city of Smendes, founder of the 21st dynasty. During the Twenty-second Dynasty Tanis remained as Egypt's political capital (though there were sometimes rival dynasties located elsewhere in Upper Egypt). It was an important commercial and strategic city until it was threatened with inundation by Lake Manzala in the 6th century AD, when it was finally abandoned. The refugees founded the nearby city of Tennis.
The Hebrew story adopted by Christianity of Moses’ being found in the marshes of the Nile River as told in Exodus 2:3-5 is commonly located at Tanis. However, the intent of those stories may be as spiritual as much as historical allegories, as no supporting archaeological evidence has been unearthed. The demise of the city may well have been siltation of Nile tributaries.