sentences:  The metals preferred were originally copper, then brass at about the end of the 15th century and finally bronze in about 1630.Early in the 18th century, Bristol, with companies such as R. & W. King (one of the companies later incorporated into the United African Company), and then Birmingham, became the most significant European brass manufacturing city.It is likely that most types of brass manillas were made there, including the "middle period" Nkobnkob-Onoudu whose weight apparently decreased over time, and the still lighter "late period" types such as Okpoho (from the Efik word for brass) and those salvaged from the "Duoro" wreck of 1843.