2017 rainfall Myanmar

What causes the low rainfall in the center?

Find the code here.

// import image collection
var chirps = ee.ImageCollection("UCSB-CHG/CHIRPS/DAILY")
chirps = chirps.filterDate("2017-01-01","2018-01-01").sum()

// filter for Vietnam
var countries = ee.FeatureCollection('ft:1tdSwUL7MVpOauSgRzqVTOwdfy17KDbw-1d9omPw');
var country_names = ['Myanmar (Burma)'];
var myCountry = countries.filter(ee.Filter.inList('Country', country_names));
var aoi = myCountry.geometry();

// add map
Map.addLayer(chirps.clip(aoi),{min:1000,max:3500,palette:"white,blue,darkblue,red,purple"},"2015 prepcipitation");