1. It appears that the land is not divided in physical form as yet.
2. IUf that is so then the sale though is valid if your brother has not sold more area of land than what he is entitled to but may amount to complications as you may claim the portion he has sold.
3. In future to ensure that he may not sold more rea of land or other properties you should file a suit for partition and injunction at once.
4.If the area left for you is not less than to what you are entitled to then put boundary on the land.
5. If any of the properties of your father situated in Kolkata then you may file suit here . Else Bihar is the place of suing.