Some of the words used in the Tehrani accent may derive from the northwestern Iranian language of Razi, such as sūsk "beetle; cockroach", jīrjīrak "cricket", zālzālak "haw(thorn)", and vejīn "weeding".
[1] The Tehrani dialect in its current form has existed since the Qajar era and is different from the language of the natives of Tehran; the old Tehrani dialect still exists in areas like Shemiran and Damavand, although it is subject to extinction.
The northern regions such as Vanak, Shemiran, and Tajrish had the Mazandarani dialect.
The southern regions of Tehran, which are adjacent to the city of Ray, had the Raji (Razi) dialect.
The western regions of Tehran towards Karaj were also affected from Tati.