From this Reuters story that we found in the Guardian, we read some of the factors that may have led to the drop.
The number of poor people fell to 32.53 million in March, from 34.96 million in the same period a year, the bureau said, based on a survey of 68,000 households. The total population is about 226 million.
The government defines those who spend less than 200,262 rupiah a month on average as below the poverty line. One of the most important factors affecting monthly spending is the price of rice, a staple food.
Rice accounts for about a quarter of monthly spending for the poor in the cities, and about 35 percent of the spending for the poor living in villages.
The price of rice rose 7.8 percent in March compared to a year ago, a slower pace than inflation over the same period, the bureau said, adding that farmers' average daily income increased around 13 percent in the period.