The following lists events that happened during 1840 in Qajar era.
Incumbents Monarch: Mohammad Shah Qajar
Births October 17 – Mirza Nasrullah Khan, first Iranian Prime Minister. ? – Abdallah Mazandarani, Iranian Shia Marja' and politician. ? – Amina Aqdas, Persian royal consort. ? – Seyyed Abdollah Behbahani, Persian Shi'a theologian. ? – Zeyn al-Abedin Maraghei, Persian novelist.
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