The phrase "eastern part" refers to the section or area that is located towards the east, or to the right, of a particular place or region. Full definition
The beach on eastern part of the island is very nice and there's snorkeling just offshore and further north. (gili-paradise.com)
Above - average precipitation fell across eastern parts of the state, but below - average precipitation across western and central parts of the state resulted in drought expanding during the season. (ncdc.noaa.gov)
A number of small airlines serve the coast and eastern part of the country. (thetravelmagazine.net)