Mongolian Time Expressions and the Case Each One Takes

There is no word for "at", and that is the whole problem

An English speaker learning to say when something happened looks for a dictionary entry: the Mongolian for at, the Mongolian for since, the Mongolian for for. There is none. Mongolian never puts a word in front of a noun to say what that noun is doing in the sentence. It marks the noun itself, with a case ending, or it puts a postposition behind it and that postposition demands a case on the word in front.

So "when" is not a question of vocabulary. It is a question of morphology, and it has a small number of answers. Once you know which of five devices a given kind of time phrase uses, you can build any of them. The five are: no ending at all; the dative-locative; the ablative; a postposition with the genitive in front of it; and a postposition with nothing in front of it.

The time words that take nothing

A large and useful group of time words are already adverbs, and they take no ending of any kind. You drop them into the sentence bare:

• өчигдөр (yesterday), өнөөдөр (today), маргааш (tomorrow)
• уржигдар (the day before yesterday), нөгөөдөр (the day after tomorrow)
• одоо (now), саяхан (recently), сая (just now), дөнгөж (only just)
• мөд and удахгүй (soon), эрт (early), хожуу (late)

This is the one corner where English and Mongolian behave the same way. You say "I came yesterday", not "I came at yesterday", and Mongolian agrees:

Би өчигдөр ирсэн.

I yesterday come-PAST

"I came yesterday."

The adverbs of frequency behave identically and take no ending either: дандаа and үргэлж (always), заримдаа (sometimes), ихэвчлэн (usually), дахин (again), одоохондоо (for now). The habit of hunting for a preposition is the habit to break first, because for this whole group there is nothing to hunt for.

A point in time: the dative-locative

The case that puts a thing somewhere also puts an event somewhen. The dative-locative, –д or –т, is what answers "at what time":

Та хэдэн цагт ирэх вэ?

you what-many hour-DAT come-PART Q

"At what time will you come?"

And the answer carries the same ending: арван цагт (at ten o'clock). Notice two things. First, the numeral itself takes nothing — арван stands in front of цаг in its attributive form and the noun stays singular, which is the behaviour described on the page about numbers before a noun. Second, the ending lands on the word цаг, not on the numeral, because it is the hour that is the location in time.

A season behaves the same way once it is named as a season. The phrase for the winter season is өвлийн улирал, and the dative-locative lands on улирал in the ordinary way: Өвлийн улиралд хүйтэн байна. ("In the winter season it is cold.") The four season words themselves — хавар, зун, намар, өвөл — are also used bare, with no ending at all, exactly like өнөөдөр.

The names of the days are ordinary nouns — Даваа гариг (Monday), Мягмар гариг (Tuesday), and so on through Ням гариг (Sunday). They are listed in the course in that bare shape only, never inflected, which leaves a gap exactly where an English speaker wants to say "on Monday". A short section near the end of this page says what fills that gap, and how far the form that fills it can be trusted.

A starting point: the ablative

English has one word, since, and another, from, and they overlap. Mongolian uses one case for both, and it is the case of coming-out-of: the ablative.

Тэр судлаач өглөөнөөс хойш хүлээсэн.

that researcher morning-ABL after wait-PAST

"That scholar has been waiting since morning."

The ablative alone is enough — маргаашнаас means "from tomorrow on", өчигдрөөс "since yesterday" — and хойш may be added behind it to make the "ever since" reading explicit. The same case appears on the question word: Та хэзээнээс Улаанбаатарт суусан бэ? ("Since when have you lived in Ulaanbaatar?"). A question word is a noun too, and it declines.

Two mechanical points about these forms belong to other pages, and it is worth knowing they are not your fault when you meet them. The vowel of the ending — –аас, –оос, –ээс or –өөс — is chosen by the vowels of the word it attaches to, and the four-form suffix table is the single place that table lives. And a short vowel in the last syllable drops out when the ending arrives, which is why өчигдөр becomes өчигдрөөс rather than anything you would have predicted from the spelling.

An end point: хүртэл, with nothing in front of it

хүртэл means "until", and it is the exception in this family: it takes no case at all on the word in front of it. The time expression simply stands there and хүртэл follows:

• хоёрдугаар сарын сүүлч хүртэл — until the end of February

Inside that phrase there is a genitive, сарын, but it belongs to сүүлч ("the end of the second month"), not to хүртэл. The postposition itself is content with a bare noun.

Duration, "ago", "before" and "after": the genitive plus a postposition

This is the group that repays learning as a single rule, because four different English expressions collapse into one Mongolian pattern: put the time noun in the genitive, and put the postposition behind it.

Set out as a gloss, the "ago" pattern looks nothing like its English counterpart:

Хоёр жилийн өмнө бид хоёр гэрлэсэн.

two year-GEN before we two marry-PAST

"Two years ago the two of us married."

English "ago" looks backwards from now and sits after its noun; өмнө means "in front of, before" and sits after its noun as well, but the noun is possessed by it: literally "in the before of two years". Note also that the numeral хоёр takes no ending while жил takes the genitive. The number stays outside the inflection; the noun carries it.

Which form of the genitive appears — –ын, –ийн, –ны and the rest — is settled on the genitive page, and it is the one case where some memorisation survives. For the common time nouns the forms are worth learning as items: жил gives жилийн, сар gives сарын, өдөр gives өдрийн, хоног gives хоногийн.

The same genitive-plus-postposition frame carries хойно (after, behind) and, with the ablative instead, эхлэн (starting from). The list of postpositions and the case each one demands is a page of its own; what matters here is that a time phrase is never built by a word placed in front.

The calendar, and why it is a chain of genitives

Months are not named in Mongolian; they are numbered. An ordinal plus сар ("moon, month") gives the month, so that нэгдүгээр сар is January and хоёрдугаар сар February; how the ordinals themselves are built is the business of the page on numbers. A full date then stacks genitives, each one possessing the next unit down: the year in the genitive, оны, then the month in the genitive, сарын, then the day. Read literally it says "of the year, of the month, the day", which is the reverse of the English order and the same order as the written numeric date.

The grammatical lesson is the chain itself, not the vocabulary: the genitive in Mongolian stands in front of what it specifies, so a date reads from the largest unit to the smallest with no "of" anywhere in sight. The words for days, months and hours themselves are vocabulary rather than grammar, and this dossier is a grammar.

Where the time phrase goes

A time expression normally follows the subject and precedes the verb, because the verb closes the sentence. It is one of the mobile elements: it can move forward for emphasis without breaking anything. The full picture of what may move and what may not is the business of the word-order page; for time expressions the practical rule is that they go in the middle and never last.

Asking when

хэзээ is "when". Like every question word it rules out уу and үү at the end of the clause it belongs to and calls for бэ or вэ instead; which of those two appears is settled on the page about question particles, not here. The half that belongs to time is the other one: as хэзээнээс showed above, a question word accepts case endings just as a noun does, so "when" becomes "since when" by the same ablative you would put on өглөө.

Beyond the method

One form this page needs is not in the course. The day names appear there in their bare shape only, so there is no worked example of "on Monday". By the rule set out above a day name takes the dative-locative like any other time noun, and since гариг ends in г the ending is –т, which gives *Даваа гаригт.

The whole system on one page

Ten rows, five devices, and not one word placed in front of a noun. The English speaker's instinct — reach for a preposition — fails on every line, and that is the single thing worth internalising before any of the individual forms.