Towards the second half of tenth century kingdom of "Thatta" was acquired by Makrab Khan by killing Shah Sadakat Khan and crowned self as "Mirak Shah". His courtiers advise him to spread Islam for getting Janat [Haven], following to this suggestion he called the leaders [Mukhi] of Hindus and kept two options of either to become followers of Islam or be ready for untimely death before them and ask for choosing one. This was a hard call for Hindus of the Sindh, as they all were aware that Mirak Shah was hardcore Islam follower.

It was not an easy decision to be taken hence the Panchs [leaders] called all Hindus, thousands were gathered on the bank of river Sindhu and prayed Jal Devata Dariyashah [water God] for safe guarding them from the cruel and undesirable actions of Mirik Shah. History says that this prayer was lost for long forty days and all the Hindus were there with same cloths, without shaving , footwear and they were having bath without oil & soap, as there was a huge gathering so they have to take very simple food. [In the present times this is celebrated as "Chaliho Saheb"]
After forty days a divine voice "Aakashwani" was heard by gathering " Don't fear, I will take birth at Nasarpur in the house of Devaki & Tarachand Lohano and will rescue you all". Hindus asked to Mirik shah for granting time for reaching to decision. As shah was knowing that Hindus were at his mercy and he can kill them at any given moment so he granted time.