A British warship stood idle during the course of the invasion. A number of options between PCL and the trucial rulers were signed, providing useful revenue for communities experiencing poverty following the collapse of the pearl trade. The remnants of the trade eventually faded away shortly after the Second World War , when the newly independent Government of India imposed heavy taxation on pearls imported from the Arab states of the Persian Gulf. The Trucial Oman Scouts was a small military force used by the British to keep the peace. Primarily in reaction to the ambitions of other European countries, namely France and Russia, the British and the Trucial Sheikhdoms established closer bonds in an treaty, similar to treaties entered into by the British with other Persian Gulf principalities. The council was terminated once the United Arab Emirates was formed. Bahrain and Qatar declined their invitations to join the union. A number of undersea oil surveys were carried out, including one led by the famous marine explorer Jacques Cousteau. A small number of hand-picked voters chose half of the members of the Federal National Council, an advisory body. By the 17th century, the Bani Yas confederation was the dominant force in most of the area now known as Abu Dhabi. The seasonal movements of these groups led to not only frequent clashes between groups but also the establishment of seasonal and semi-seasonal settlements and centres. Furthermore, some people have had their nationality revoked. By , it had become clear the British government could no longer afford to administer and protect what is now the United Arab Emirates. Piracy in the Persian Gulf A map of the area in The harsh desert environment led to the emergence of the "versatile tribesman", nomadic groups who subsisted due to a variety of economic activities, including animal husbandry, agriculture and hunting. In March, it struck oil in the Upper Thamama, a rock formation that would provide many valuable oil finds. The seven sheikhs of the emirates then decided to form a council to coordinate matters between them and took over the development office.