The centre of many cultures is a deep rooted anchor for courtesy and respect.
The most common word to learn in any language is
In Persian [Fars] we have many ways to say thank you. Formal and informal methods also play a role when speaking to those that are your senior or those that you are only acquaintances with.
Is a great baseline for anyone who you have just met, and is a respectful and general way of saying thank you in Persian [Fársí]
This almost directly translates to im so very grateful.
Mersí is actually a loan word from the French! and is the most informal way of saying thank you in Iran.