Learn Hardcore German: Die Erschöpften sitzen am Lagerfeuer und trinken Tee. - The exhausted ones sit by the campfire and drink tea.

Erschöpften comes from the adjective erschöpft (“exhausted”), but here it is used as a noun: die Erschöpften = “the exhausted (people)”.
In German, when an adjective is used on its own to stand for a person or group, it is written with a capital letter.
So die Erschöpften literally means “the exhausted ones” or “the exhausted people.”

Why does Erschöpften end in -en and not -e (why not die Erschöpften vs die Erschöpften with -e)?

The -en ending comes from adjective declension rules.
We have:

Article: die (definite article, plural, nominative)
Adjective used as noun: erschöpft-

With die in the plural, the adjective takes the weak ending -en in nominative plural:
die Erschöpften = nominative plural.

If there were no article, you would get the strong ending:
Erschöpfte sitzen am Lagerfeuer. (“Exhausted people are sitting at the campfire.”)

Is die Erschöpften singular or plural? Does it have a gender?

In this sentence, die Erschöpften is plural – it refers to several exhausted people.
The form die + -en ending signals plural here.

As a “noun made from an adjective,” it doesn’t have just one fixed gender; its gender is understood from context:

der Erschöpfte – the exhausted man (masculine singular)
die Erschöpfte – the exhausted woman (feminine singular)
das Erschöpfte – the exhausted thing (neuter singular, rare here)
die Erschöpften – the exhausted (people) (plural, all genders together)

In this sentence, it clearly means “the exhausted people” in general.

What case is die Erschöpften in here?

Die Erschöpften is in the nominative plural.
You can tell because:

It is the subject of the verbs sitzen and trinken.
The plural article die and the adjective ending -en with a definite article fit nominative plural.

So:
Wer sitzt am Lagerfeuer? – Die Erschöpften.
(“Who is sitting at the campfire? – The exhausted (people).”)

Why do we have two verbs, sitzen and trinken, and how is that allowed in German word order?

The subject die Erschöpften has two actions:

They sitzen (are sitting)
and they trinken (are drinking)

German allows you to join two main verbs with und when they share the same subject:

Die Erschöpften sitzen am Lagerfeuer und trinken Tee.

The finite verb must still stay in second position in each clause. Here, it’s really one clause where both verbs belong to the same subject. You could also say:

Die Erschöpften sitzen am Lagerfeuer und sie trinken Tee.
(two explicit clauses with the subject repeated)

What does am Lagerfeuer mean exactly, and what is am?

Am is a contraction of an dem:

an = at / on (depending on context)
dem = the (dative singular, masculine or neuter)

So am Lagerfeuer = an dem Lagerfeuer = “at the campfire.”
The preposition an with a static location (where someone is) takes dative case, which is why we have dem and not den.

What case is Lagerfeuer in, and why doesn’t it change its form?

Lagerfeuer is neuter singular, dative:

Article: dem (becomes am when contracted)
Noun: Lagerfeuer

So, grammatically: an + dem Lagerfeuer (dative).
Most neuter nouns in German do not change their form in the dative singular, so the word stays Lagerfeuer. The case is only visible in the article (dem → am).

What exactly is Lagerfeuer? Is it a compound word?

Yes, Lagerfeuer is a compound noun:

das Lager = camp
das Feuer = fire

Put together: das Lagerfeuer = “campfire.”
In German, the last part of a compound decides the gender, so Lagerfeuer is neuter: das Lagerfeuer.

Why is there no article before Tee? Could I say den Tee or einen Tee instead?

Here, Tee is used in a general, indefinite sense: they are drinking tea, not a specific tea that was mentioned before. In this kind of generic use, German often omits the article with mass nouns:

Sie trinken Tee. – They are drinking tea (in general).

You could say:

Sie trinken einen Tee. – They are drinking a (cup of) tea.
Sie trinken den Tee. – They are drinking the tea (that we already talked about or that is clearly identified).

All are grammatically correct, but the meaning shifts from general to more specific.

Could I say Sie sind erschöpft und sitzen am Lagerfeuer instead of Die Erschöpften sitzen ...? What’s the difference?

Yes, you could say:

Sie sind erschöpft und sitzen am Lagerfeuer und trinken Tee.

This uses erschöpft as a normal predicate adjective (“they are exhausted”).

In the original sentence, die Erschöpften makes “the exhausted” sound like a defined group or category – almost like a label:

Die Erschöpften sitzen am Lagerfeuer … – “The exhausted (people) are sitting at the campfire …”

It’s a bit more literary or descriptive and puts emphasis on their condition as their defining feature.

How would the sentence change if it were just one exhausted person instead of several?

You’d have to change subject, verbs, and adjective ending to singular. For example:

Der Erschöpfte sitzt am Lagerfeuer und trinkt Tee. – one exhausted man
Die Erschöpfte sitzt am Lagerfeuer und trinkt Tee. – one exhausted woman

Notice:

Article + adjective-as-noun change:
- der Erschöpfte, die Erschöpfte (singular, nominative)
Verbs change to singular:
- sitzt, trinkt

Does sitzen here mean “are sitting” (progressive) like in English, even though German doesn’t have a continuous tense?

Yes. German usually uses the simple present to cover both:

English simple present: “they sit”
English present continuous: “they are sitting”

So Die Erschöpften sitzen am Lagerfeuer is naturally understood as:

“The exhausted (people) are sitting at the campfire”

German can use extra words like gerade (“right now”) if you want to stress the ongoing action:
Die Erschöpften sitzen gerade am Lagerfeuer und trinken Tee.

Are there other common examples of adjectives used as nouns like die Erschöpften?

Yes, this pattern is very common. Some frequent examples:

der Deutsche / die Deutsche / die Deutschen – the German (person) / the Germans
der Alte / die Alte / die Alten – the old man / the old woman / the old people
die Reichen – the rich (people)
die Kranken – the sick (people, the patients)

In all these, an adjective is capitalized and declined like a normal adjective, but it stands in for the noun (person/people).