先达是印度尼西亚的城市，由北苏门答腊省负责管辖，位于该国西北部苏门答腊岛北部，面积79.97平方公里，2010年人口234,885，人口密度为每平方公里2,937.16人。

Pematangsiantar (sometimes written as Pematang Siantar, acronym PT. Siantar or P. Siantar, colloquially just Siantar, Jawi: ڤيماتاڠسيانتار‎, Chinese:先达; pinyin:Xiān dá), is an independent city in North Sumatra, Indonesia, surrounded by, but not part of, the Simalungun Regency. Pematangsiantar formerly had the status of a second level district (daerah tingkat dua) and has recently been elevated to Kota (City) - its population was 219,319 in the 1990 Census, 242,756 in the 2000 Census, and 240,787 in the 2010 Census, making it the second largest city in the province after the provincial capital Medan.