=how did the development of state power result in
external and internal challenges in the period between
1450 and 1750?

The years between 1450 to 1750 is called the Early Modern Era.

Explanation:

During this period, the British were inclined to expand its territorial limits. The emergence of Dutch East India Company and the extension of the Spanish empire occurred during this period and on the whole the imperialism of Europe began.  

Apart from the existence maritime empires, there were also large land empires such as Islamic and Ottoman Empire existed. Transoceanic voyages were possible which increased the trade relationships with the west. Global transaction of goods enabled Columbian exchange.

what do you mean

general allotment act (dawes act) february 8, 1887

amendment to the dawes act, february 28, 1891

commission to the five civilized tribes (dawes commission), march 3, 1893