The Manussan held artwork in high regard. Figures such as Ambril hoarded such relics and formed museums. The Mara's origins in Manussan society meant that snakes played a large part in celebrations, with large snake models being paraded through towns on occasion. Such practices as that of the Attendant demon were also important in celebrations. (TV: Snakedance)
The Manussan were a very advanced civilivation, allowing them to branch out and form the Manussan Empire. At one point they created the Great Crystal using the power of their minds, which accidentally created the Mara. This resulted in the fall of the empire, which made way for the Sumaran Empire.
When the Mara returned to Manussa via Tegan Jovanka, it possessed Lon, a highly regarded figure. It was only through the help of the Fifth Doctor that the Mara did not gain a new physical form. (TV: Snakedance)