とあって

conjunction

because; due to the fact that; given that

Conjunction used to state a reason or cause, often with a nuance of 'precisely because' or 'as might be expected from'. Typically follows a clause ending in a noun, na-adjective, or plain form of verbs/i-adjectives. More formal and emphatic than から or ので.

• 今日きょうは祝しゅく日じつとあって、街まちは静しずかだった。

  Given that today is a national holiday, the streets were quiet.

• 人にん気き歌か手しゅのコンサートとあって、会かい場じょうは満まん員いんだった。

  Because it was a concert by a popular singer, the venue was packed.