original: Initially about 30,000 people moved to the goldfields, but by 1863 this had declined to about 3,500 because of the difficult mining conditions.
simplifications: About 30,000 people moved to the goldfields, but by 1863 this had declined to about 3,500 because of the difficult mining conditions. At the beginning 30,000 people moved to the goldfields. By 1863 only 3,500 moved there because of the difficult mining conditions. About 30,000 people moved to the goldfields. This had declined to about 3,500 because of the difficult mining conditions by 1863. About 30,000 people moved to the goldfields at first. By 1863, this had dropped to about 3,500 because of the difficult mining conditions. Initially about 30,000 people moved to the goldfields. By 1863 it had declined to about 3,500 because of difficult mining conditions. At first, about 30,000 people moved to the goldfields. By 1863, only 3,500 were left because of the difficult mining conditions. At first, around 30,000 people moved to the goldfields. This had declined to about 3,500  by 1863. The decline in population was because of difficult mining conditions. Almost 30,000 people moved to the goldfields. The hard mining conditions left about 3,500 people there by 1863. At first around  30,000 people moved to the goldfields. By 1863, this number dropped to about 3,500. This decrease in number was because of difficult mining conditions. Briefly about 30,000 people moved to the goldfields, but by 1863 this had decreased to about 3,500 due to difficult mining conditions.