The world thinks that Akbar was responsible for banning of marriages of Mughal princess(daughters, grand daughters, great grand daughters etc) but this is just a rumour. Neither Akbarnama, Jehangirnama, Shahjahan nama or Aurangzeb’s royal court chronicles ever mention Akbar or any emperor banning Mughal princess marriage. But the Mughals had one practise that they all married only withing their close relatives.
Akbar married Ruqaiah and Salima his cousin sisters first not any outside princess.
All of Akbar’s daughters were married except Aram Banu who stayed with her brother Jehangir till she died(after him). Akbar’s two daughters Aram and Khanum are buried in Akbar’s tomb at Sikandara.
Jehangir himself married three of his cousins- his first three marraiges were to his Rajput cousin sisters Manwati, Jodh Bai etc.
Jehangir had 2 daughters one was Khusrau’s sister Sultan al Nisa Bano. Nur Jahan made her life miserable since her brother Khusrau had rebelled against Jehangir and she did not marry at all and stayed with her father Jehangir. Another reason was that both Daniyal and Murad’s sons were very younger compared to her hence she had no suitable groom to marry. So she lived a lonely life in company of her brothers and sisters at Agra fort. She oversaw construction of Khusrau bagh in Allahabad where her mother Manwati Bai and brother Khusrau was buried. She herself was buried next to her brother and mother after death. Since her brother and sister-in-law were in house arrest at agra fort after rebellion she took up responsibility to bring up Khusrau’s children. Jehangir’s younger daughter married Jehangir’s yournger brother Daniyal’s son and lived a happy life till Shahjahan killed her husband after her father’s death. Jehangir’s younger daughter preferred to be buried next to her grandfather after death and not her father. So you can see her grave in Sikandra in Akbar’s tomb. Jehangir’s elder daughter was buried with her brother in Khusrau bagh.
Shah Jahan’s both daughters never married not because someone banned Mughal princess marriage but because Sahh Jahan killed all his male relatives. He killed all his brothers their sons and all of Jehangir’s brother’s Daniyal and Murad’s son’s and their sons and all of Akabr’s step brother’s sons and grandsons. So no male was actually left to marry Jahanara and Roshanara in that generation.
Next generation again Aurangzeb’s daughters married their uncle Shah Sujah and Dara Sukoh’s sons. This practice continued in all generations of Mughals. So it is a myth that Akbar banned Mughal princess marraige.
Now how was this practice established.
First Mughals did not want a son-in-law competing for the Mughal throne so usually they inter married withing brothers and sisters children. So even if son-in-law became emperor he will be blood relative of emperor. This problem arose after Akbar’s brother-in-law and son-in-law both rebelled because they wanted to be emperor and were not his close relatives. So they decided to intermarry among siblings children in future generations.
Second Mughals did not want their daughters and sisters marrying to anyone lower in status to them. Because of many rebellions and incidents like Sharifuddin etc
Third Mughals men although married hindu princess, did not want their daughters and sisters marrying a hindu prince and converting to another religion. This was also because in hindu society at that time a wife, widow etc did not have many rights whereas in muslims girls could divorce, remarry, no sati and also their status did not change with husband death like in case of hamida banu who remained mailka-e-azam after husband death. So the girls could only inter marry within family to avoid these three issues or could remain unmarried if they did not wish to marry or did not get suitable grooms within relatives.
And majority of the Mughal princes and emperor’s favourite wives were their own cousins.