Governing a country that was mainly agricultural, both things worried Don Carlos, especially the establishment of a good industry for the land. Yanguas writes in this regard:
"In 1376 he lent 500 pounds to the council of Larraga to build a dam on the Arga River. In 1366 he ordered a house to be rented in Estella for a clothier, a dyer and a weaver, whom he had ordered to come from Aragon to make cloth, and that the bailiff and the receiver should pay them without excuse the wages that were praised, under penalty of doing it from their own pockets. In 1372 he ordered 30 florins to be paid to Miguel de Mazas, a clothier, to Valero de Zaragoza, a pilater, and to Master Bernar, a dyer, whom he had brought from Zaragoza to see where in his kingdom clothiers could be made well, mainly in Pamplona, Puente la Reina and Estella. At the same time he sent Don Ponz Eslava and Zalema Zaragozano, a Moor, to Zaragoza to examine in what manner The mills, boilers, drawbars and other devices with which the cloths were made were made. In 1376 he ordered the making of a baton to dress the cloths in the mill of the bridge of Tudela."