Aanam means cattle,it is named for the idolaters making some cattle lawful and others unlawful for superstitious reasons and them being refuted for this, the surah has 165 verses covering only one topic. This is unique in the Qur’an because most surahs cover several topics. This surah covers the pillars of faith. It was revealed in one setting and it was revealed in Mecca.
The woman Asma was leading a she-camel and the Prophet (S) was riding it and when he received this surah the camel stopped and looked as though it was carrying a heavy load all of a sudden, and didn’t move until the revelation was finished. Allah says the Qur’an is the heaviest thing. Not just heavy in meaning, it is physically heavy. If you stand to recite a large portion of it you will be physically drained. Asma came to visit the Prophet (S) from Madina to learn from the Prophet (S) in Mecca. She narrated this story of the Prophet (S) receiving the surah. Her being there for the revelation shows the importance of women in carrying on this Deen.