It's not what you asked, but it's similar enough that I think we should mention it. A similar practice is associated with the Ottoman Empire for a very simple reason: up until the 17th century the Empire (like many Muslim states at the time) did not have a clear succession rule beyond "be a member of the dynasty". Any child could inherit... which led to civil war. So in the mid 15th to the late 16th century it was the legal for the new sultan... to execute his brothers (at least those that could challenge him). After enough public outcry the practice was abolished and a proper succession order was made around 1600, after that the eldest son inherited the throne... the others were imprisoned (in a golden cage, but still) to prevent any trouble.