The Castillian Order of the Band was founded in 1332, when king Alfonso XI ordered some of the knights and squires of his retinue to dress, like him, in white cloth with the band "that he had given them". A few years before that, in 1324, it's written that a knight was rewarded for his participation in the defense of Baéza; he was specifically awarded the right to bear ornaments of gold and silver, as he was a knight of the band of gold.
The order was of the non-religious, courtly type. Its members were to participate in jousts and be supportive and loyal to the king of Castile. The rules of those jousts and the type of support expected were specified in the rules of the order, which also included notes on suitable behaviour.
The colours of the Band changed over time, as did the importance and character of the order. The Band was adopted by successive monarchs, who came to see the order as part of the royal institution. It widened its base and in the 15th century the band was awarded to women as a device. During the 15th century the order entered a period of decadence; it's considered to have been extinct by around 1474.