1642年荷蘭東印度公司從西班牙手中取得北部臺灣後，荷蘭在福爾摩沙當時的商業與殖民活動得以擴及到全島。基於大員為東印度公司在臺灣的根據地，北臺的發展重心，除了初期以軍事行動為主外，行政與經濟的重要地位逐漸由雞籠移轉到淡水。筆者將此一過程大略分成雞籠轄淡水時期（1642-1643年）、轉型過渡期（1644-1645年），與淡水轄雞籠時期（1645-1662年）三個階段。1645年8月公司在淡水設立主管一職，使淡水更具體成為大員與雞籠兩地之間的中繼站，擔負起人員、貨物與命令的匯集與分配等樞紐的角色。淡水也串連起位居北臺與大員所在區域之間廣大的新領地。如何強化北臺地區、新領地與西南部平原核心地區的連結，同時將荷蘭東印度公司成為「整座島嶼的主人」的現狀轉化成具體的經濟利益，將是本文觀察與分析的重點。

The Dutch conquest of Spanish Formosa in 1642 initiated an island-wide colonial expansion of Dutch East India Company (VOC) in Taiwan. For the purpose of connecting Tayouan in the core area and northern Formosa, Tamsuy, the nearest settlement in the region, played a pivotal role in Company's formulation on the newly acquired territories. The author proposes that three stages can be observed in this process: Quelang over Tamsuy, 1642-1643; a transitional period, 1644-1645, and Tamsuy over Quelang, 1645-1662.In August, 1645, the introduction of opperhoofd in Tamsuy marked the changing center of power and authority in northern Formosa. Quelang gradually won its military tone. In order to open the Tamsuy Route between Tayouan and Tamsuy, the Dutch authorities made efforts to defeat aboriginal villages along the region, including the powerful Quataongh. These conquests, creating more leasehold divisions into the village leasehold system, made more profits in accordance with the status quo as 'the sole master in the whole island'. However, by the end of 1650s, northern Formosa failed to continuously lure the Dutch, due to financial hardship, difficulties in maintenance and supply, as well as unpleasant environment for the Dutch residents. The Dutch reluctance to retain this burden of northern Formosa was to prevent the presumed occupation by the local Chinese who had been encouraged to settle down in this region by the authorities but now might incite the Formosans to resist the Company.