I'm honestly really impressed with just how much information there is in the first chapter of ISStH alone, especially since I've already read it through in the past.
In the span of 2000 words, Er Gen:
Introduces four characters (The protagonist Meng Hao, two of his friends, and the female lead.)
Establishes the main character's motivations, personality, and past.
Sets in motion the main plot by kidnapping our protagonist.
Loads at least two Chekhov's Guns (Meng Hao was abandoned by his parents, wants to go to the Great Tang in the Eastern Lands, and throws a gourd into a river. All three of these things will come back later.)
Overall, the first chapter of ISStH already is doing a lot to build out the world. The second chapter will be doing more of the same.