By the middle of the eighteenth century the Dutch had established themselves in all sections of the Essequibo region. Using Kykoveral, and later Fort Island, as their base of operations, Dutch traders and agents appointed by the Director General travelled to various locations by foot and canoe. They established contacts with various Amerindian villages with which they traded European goods for annatto dye, letter-wood, and crab oil.

The Essequibo River was established as the main communication route and by the third decade of the century, a post was set up at the junction of the Siparuni and Essequibo Rivers. (In 1756, this post, known as Arinda, was shifted further upwards to the junction of the Rupununi and Essequibo Rivers).

Beginning from the early 1740s, the Director General, Gravesande, took steps to establish total control of the Essequibo basin. He sent Nicolas Hortsman, a surveyor, to locate the source of the river and plant the Dutch flag there. This task was carried out, but shortly after, Hortsman deserted to work for the Portuguese in Brazil just south of the source of the Essequibo.

In the area of the Mazaruni River, the Dutch established both company and private plantations. Trading was also conducted with the Amerindians who lived there. Gravesande clearly regarded the Mazaruni basin as Dutch territory, and on one occasion when he learned that Amerindians loyal to the Spanish had moved into the area, he sent a force of loyal Caribs to eject them.

The Dutch established a Post on the upper Cuyuni river as early as 1680 in the Pariacot savannah to trade with the Amerindians. (This savannah is located north and west of the Yuruari River to the banks of the Cuyuni - areas which are now part of Venezuela). An intermittent vibrant trade in horses from the Spanish settlers further west in the Orinoco developed from this time. The horses were herded along a trail on the bank of the Cuyuni to Kykoveral from where they were sent to the sugar-mills on the Essequibo plantations.

This trail was also used by runaway African and Amerindian slaves who fled from the Dutch plantations to Venezuela. A Frenchman, Ignatius Courthial, contracted by the Dutch authorities in Essequibo, thought of using this trail to build a road from Demerara to the upper Cuyuni. He drew up a plan for this project which Gravesande, on a visit to Holland in 1750, presented to the Zeeland Chamber. There was an actual start to this project, but, most likely through a shortage of funds or because the Dutch wanted to stop the steady escape of slaves along this route, it was halted.

In the North West District, the Dutch by the beginning of the eighteenth century were in control of the basins of the Pomeroon, Moruca, Waini and Barima Rivers. In Barima, a small French settlement was established in 1689 but was abandoned shortly after, even though traders from Martinique continued to trade with the Amerindians there. In 1734, there were reports that the Swedes were planning to settle in the area. However, this never occurred.

Gravesande, from the time he became the Director-General of Essequibo, regarded the right bank of the Barima as Dutch territory and the left as Spanish. But, interestingly, the Spanish were firm in the opinion that both banks belonged to the Dutch. This was stated very clearly in 1766 when the Spanish Governor of the Orinoco, after being requested by Gravesande to arrest a gang of criminals who were based on the left bank, replied that he felt the Dutch Director-General had jurisdiction to make the arrest.